diff --git a/configure b/configure
index 2e06a72..d8f8e88 100755
--- a/configure
+++ b/configure
@@ -699,6 +699,8 @@ SHELL'
 ac_subst_files=''
 ac_user_opts='
 enable_option_checking
+with_sdl_prefix
+with_sdl_ttf_prefix
 '
       ac_precious_vars='build_alias
 host_alias
@@ -1322,6 +1324,13 @@ if test -n "$ac_init_help"; then
    esac
   cat <<\_ACEOF
 
+Optional Packages:
+  --with-PACKAGE[=ARG]    use PACKAGE [ARG=yes]
+  --without-PACKAGE       do not use PACKAGE (same as --with-PACKAGE=no)
+  --with-sdl-prefix=DIR   Specify the prefix directory for SDL2
+  --with-sdl-ttf-prefix=DIR
+                          Specify the prefix directory for SDL2_ttf
+
 Some influential environment variables:
   CC          C compiler command
   CFLAGS      C compiler flags
@@ -1483,6 +1492,53 @@ printf "%s\n" "$ac_res" >&6; }
   eval $as_lineno_stack; ${as_lineno_stack:+:} unset as_lineno
 
 } # ac_fn_c_check_header_compile
+
+# ac_fn_c_try_link LINENO
+# -----------------------
+# Try to link conftest.$ac_ext, and return whether this succeeded.
+ac_fn_c_try_link ()
+{
+  as_lineno=${as_lineno-"$1"} as_lineno_stack=as_lineno_stack=$as_lineno_stack
+  rm -f conftest.$ac_objext conftest.beam conftest$ac_exeext
+  if { { ac_try="$ac_link"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval ac_try_echo="\"\$as_me:${as_lineno-$LINENO}: $ac_try_echo\""
+printf "%s\n" "$ac_try_echo"; } >&5
+  (eval "$ac_link") 2>conftest.err
+  ac_status=$?
+  if test -s conftest.err; then
+    grep -v '^ *+' conftest.err >conftest.er1
+    cat conftest.er1 >&5
+    mv -f conftest.er1 conftest.err
+  fi
+  printf "%s\n" "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; } && {
+	 test -z "$ac_c_werror_flag" ||
+	 test ! -s conftest.err
+       } && test -s conftest$ac_exeext && {
+	 test "$cross_compiling" = yes ||
+	 test -x conftest$ac_exeext
+       }
+then :
+  ac_retval=0
+else $as_nop
+  printf "%s\n" "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+	ac_retval=1
+fi
+  # Delete the IPA/IPO (Inter Procedural Analysis/Optimization) information
+  # created by the PGI compiler (conftest_ipa8_conftest.oo), as it would
+  # interfere with the next link command; also delete a directory that is
+  # left behind by Apple's compiler.  We do this before executing the actions.
+  rm -rf conftest.dSYM conftest_ipa8_conftest.oo
+  eval $as_lineno_stack; ${as_lineno_stack:+:} unset as_lineno
+  as_fn_set_status $ac_retval
+
+} # ac_fn_c_try_link
 ac_configure_args_raw=
 for ac_arg
 do
@@ -2267,7 +2323,7 @@ ac_compiler_gnu=$ac_cv_c_compiler_gnu
 ac_config_headers="$ac_config_headers src/config.h"
 
 
-# Checks for header files.
+# Checks for programs.
 
 
 
@@ -3264,6 +3320,140 @@ ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $
 ac_compiler_gnu=$ac_cv_c_compiler_gnu
 
 
+
+  # Find a good install program.  We prefer a C program (faster),
+# so one script is as good as another.  But avoid the broken or
+# incompatible versions:
+# SysV /etc/install, /usr/sbin/install
+# SunOS /usr/etc/install
+# IRIX /sbin/install
+# AIX /bin/install
+# AmigaOS /C/install, which installs bootblocks on floppy discs
+# AIX 4 /usr/bin/installbsd, which doesn't work without a -g flag
+# AFS /usr/afsws/bin/install, which mishandles nonexistent args
+# SVR4 /usr/ucb/install, which tries to use the nonexistent group "staff"
+# OS/2's system install, which has a completely different semantic
+# ./install, which can be erroneously created by make from ./install.sh.
+# Reject install programs that cannot install multiple files.
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for a BSD-compatible install" >&5
+printf %s "checking for a BSD-compatible install... " >&6; }
+if test -z "$INSTALL"; then
+if test ${ac_cv_path_install+y}
+then :
+  printf %s "(cached) " >&6
+else $as_nop
+  as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
+for as_dir in $PATH
+do
+  IFS=$as_save_IFS
+  case $as_dir in #(((
+    '') as_dir=./ ;;
+    */) ;;
+    *) as_dir=$as_dir/ ;;
+  esac
+    # Account for fact that we put trailing slashes in our PATH walk.
+case $as_dir in #((
+  ./ | /[cC]/* | \
+  /etc/* | /usr/sbin/* | /usr/etc/* | /sbin/* | /usr/afsws/bin/* | \
+  ?:[\\/]os2[\\/]install[\\/]* | ?:[\\/]OS2[\\/]INSTALL[\\/]* | \
+  /usr/ucb/* ) ;;
+  *)
+    # OSF1 and SCO ODT 3.0 have their own names for install.
+    # Don't use installbsd from OSF since it installs stuff as root
+    # by default.
+    for ac_prog in ginstall scoinst install; do
+      for ac_exec_ext in '' $ac_executable_extensions; do
+	if as_fn_executable_p "$as_dir$ac_prog$ac_exec_ext"; then
+	  if test $ac_prog = install &&
+	    grep dspmsg "$as_dir$ac_prog$ac_exec_ext" >/dev/null 2>&1; then
+	    # AIX install.  It has an incompatible calling convention.
+	    :
+	  elif test $ac_prog = install &&
+	    grep pwplus "$as_dir$ac_prog$ac_exec_ext" >/dev/null 2>&1; then
+	    # program-specific install script used by HP pwplus--don't use.
+	    :
+	  else
+	    rm -rf conftest.one conftest.two conftest.dir
+	    echo one > conftest.one
+	    echo two > conftest.two
+	    mkdir conftest.dir
+	    if "$as_dir$ac_prog$ac_exec_ext" -c conftest.one conftest.two "`pwd`/conftest.dir/" &&
+	      test -s conftest.one && test -s conftest.two &&
+	      test -s conftest.dir/conftest.one &&
+	      test -s conftest.dir/conftest.two
+	    then
+	      ac_cv_path_install="$as_dir$ac_prog$ac_exec_ext -c"
+	      break 3
+	    fi
+	  fi
+	fi
+      done
+    done
+    ;;
+esac
+
+  done
+IFS=$as_save_IFS
+
+rm -rf conftest.one conftest.two conftest.dir
+
+fi
+  if test ${ac_cv_path_install+y}; then
+    INSTALL=$ac_cv_path_install
+  else
+    # As a last resort, use the slow shell script.  Don't cache a
+    # value for INSTALL within a source directory, because that will
+    # break other packages using the cache if that directory is
+    # removed, or if the value is a relative name.
+    INSTALL=$ac_install_sh
+  fi
+fi
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $INSTALL" >&5
+printf "%s\n" "$INSTALL" >&6; }
+
+# Use test -z because SunOS4 sh mishandles braces in ${var-val}.
+# It thinks the first close brace ends the variable substitution.
+test -z "$INSTALL_PROGRAM" && INSTALL_PROGRAM='${INSTALL}'
+
+test -z "$INSTALL_SCRIPT" && INSTALL_SCRIPT='${INSTALL}'
+
+test -z "$INSTALL_DATA" && INSTALL_DATA='${INSTALL} -m 644'
+
+
+# User-specified SDL2 path.
+
+# Check whether --with-sdl-prefix was given.
+if test ${with_sdl_prefix+y}
+then :
+  withval=$with_sdl_prefix; sdl_prefix=$withval
+else $as_nop
+  sdl_prefix=""
+fi
+
+
+if test -n "$sdl_prefix"; then
+  CFLAGS="$CFLAGS -I$sdl_prefix/include"
+  LDFLAGS="$LDFLAGS -L$sdl_prefix/lib"
+fi
+
+# User-specified SDL2_ttf path.
+
+# Check whether --with-sdl-ttf-prefix was given.
+if test ${with_sdl_ttf_prefix+y}
+then :
+  withval=$with_sdl_ttf_prefix; sdl_ttf_prefix=$withval
+else $as_nop
+  sdl_ttf_prefix=""
+fi
+
+
+if test -n "$sdl_ttf_prefix"; then
+  CFLAGS="$CFLAGS -I$sdl_ttf_prefix/include/SDL2"
+  LDFLAGS="$LDFLAGS -L$sdl_ttf_prefix/lib"
+fi
+
+# Validate SDL2 installation.
+
 ac_header= ac_cache=
 for ac_item in $ac_header_c_list
 do
@@ -3293,6 +3483,115 @@ then :
 printf "%s\n" "#define STDC_HEADERS 1" >>confdefs.h
 
 fi
+ac_fn_c_check_header_compile "$LINENO" "SDL2/SDL_ttf.h" "ac_cv_header_SDL2_SDL_ttf_h" "$ac_includes_default"
+if test "x$ac_cv_header_SDL2_SDL_ttf_h" = xyes
+then :
+  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: SDL2_ttf headers found" >&5
+printf "%s\n" "$as_me: SDL2_ttf headers found" >&6;}
+else $as_nop
+  as_fn_error $? "SDL2_ttf headers not found in $sdl2_ttf_prefix/include/SDL2" "$LINENO" 5
+fi
+
+
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for TTF_Init in -lSDL2_ttf" >&5
+printf %s "checking for TTF_Init in -lSDL2_ttf... " >&6; }
+if test ${ac_cv_lib_SDL2_ttf_TTF_Init+y}
+then :
+  printf %s "(cached) " >&6
+else $as_nop
+  ac_check_lib_save_LIBS=$LIBS
+LIBS="-lSDL2_ttf  $LIBS"
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+/* Override any GCC internal prototype to avoid an error.
+   Use char because int might match the return type of a GCC
+   builtin and then its argument prototype would still apply.  */
+char TTF_Init ();
+int
+main (void)
+{
+return TTF_Init ();
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"
+then :
+  ac_cv_lib_SDL2_ttf_TTF_Init=yes
+else $as_nop
+  ac_cv_lib_SDL2_ttf_TTF_Init=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.beam \
+    conftest$ac_exeext conftest.$ac_ext
+LIBS=$ac_check_lib_save_LIBS
+fi
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_SDL2_ttf_TTF_Init" >&5
+printf "%s\n" "$ac_cv_lib_SDL2_ttf_TTF_Init" >&6; }
+if test "x$ac_cv_lib_SDL2_ttf_TTF_Init" = xyes
+then :
+  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: SDL2_ttf library found" >&5
+printf "%s\n" "$as_me: SDL2_ttf library found" >&6;}
+else $as_nop
+  as_fn_error $? "SDL2_ttf library not found in $sdl2_ttf_prefix/lib" "$LINENO" 5
+fi
+
+
+ac_fn_c_check_header_compile "$LINENO" "SDL2/SDL.h" "ac_cv_header_SDL2_SDL_h" "$ac_includes_default"
+if test "x$ac_cv_header_SDL2_SDL_h" = xyes
+then :
+  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: SDL2 headers found" >&5
+printf "%s\n" "$as_me: SDL2 headers found" >&6;}
+else $as_nop
+  as_fn_error $? "SDL2 headers not found in $sdl2_prefix/include/SDL2" "$LINENO" 5
+fi
+
+
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for SDL_Init in -lSDL2" >&5
+printf %s "checking for SDL_Init in -lSDL2... " >&6; }
+if test ${ac_cv_lib_SDL2_SDL_Init+y}
+then :
+  printf %s "(cached) " >&6
+else $as_nop
+  ac_check_lib_save_LIBS=$LIBS
+LIBS="-lSDL2  $LIBS"
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+/* Override any GCC internal prototype to avoid an error.
+   Use char because int might match the return type of a GCC
+   builtin and then its argument prototype would still apply.  */
+char SDL_Init ();
+int
+main (void)
+{
+return SDL_Init ();
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"
+then :
+  ac_cv_lib_SDL2_SDL_Init=yes
+else $as_nop
+  ac_cv_lib_SDL2_SDL_Init=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.beam \
+    conftest$ac_exeext conftest.$ac_ext
+LIBS=$ac_check_lib_save_LIBS
+fi
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_SDL2_SDL_Init" >&5
+printf "%s\n" "$ac_cv_lib_SDL2_SDL_Init" >&6; }
+if test "x$ac_cv_lib_SDL2_SDL_Init" = xyes
+then :
+  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: SDL2 library found" >&5
+printf "%s\n" "$as_me: SDL2 library found" >&6;}
+else $as_nop
+  as_fn_error $? "SDL2 library not found in $sdl2_prefix/lib" "$LINENO" 5
+fi
+
+
+# Checks for header files.
 ac_fn_c_check_header_compile "$LINENO" "stdlib.h" "ac_cv_header_stdlib_h" "$ac_includes_default"
 if test "x$ac_cv_header_stdlib_h" = xyes
 then :
@@ -3337,839 +3636,6 @@ then :
 fi
 
 
-# Checks for programs.
-ac_ext=c
-ac_cpp='$CPP $CPPFLAGS'
-ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5'
-ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
-ac_compiler_gnu=$ac_cv_c_compiler_gnu
-if test -n "$ac_tool_prefix"; then
-  # Extract the first word of "${ac_tool_prefix}gcc", so it can be a program name with args.
-set dummy ${ac_tool_prefix}gcc; ac_word=$2
-{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
-printf %s "checking for $ac_word... " >&6; }
-if test ${ac_cv_prog_CC+y}
-then :
-  printf %s "(cached) " >&6
-else $as_nop
-  if test -n "$CC"; then
-  ac_cv_prog_CC="$CC" # Let the user override the test.
-else
-as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
-for as_dir in $PATH
-do
-  IFS=$as_save_IFS
-  case $as_dir in #(((
-    '') as_dir=./ ;;
-    */) ;;
-    *) as_dir=$as_dir/ ;;
-  esac
-    for ac_exec_ext in '' $ac_executable_extensions; do
-  if as_fn_executable_p "$as_dir$ac_word$ac_exec_ext"; then
-    ac_cv_prog_CC="${ac_tool_prefix}gcc"
-    printf "%s\n" "$as_me:${as_lineno-$LINENO}: found $as_dir$ac_word$ac_exec_ext" >&5
-    break 2
-  fi
-done
-  done
-IFS=$as_save_IFS
-
-fi
-fi
-CC=$ac_cv_prog_CC
-if test -n "$CC"; then
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $CC" >&5
-printf "%s\n" "$CC" >&6; }
-else
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: no" >&5
-printf "%s\n" "no" >&6; }
-fi
-
-
-fi
-if test -z "$ac_cv_prog_CC"; then
-  ac_ct_CC=$CC
-  # Extract the first word of "gcc", so it can be a program name with args.
-set dummy gcc; ac_word=$2
-{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
-printf %s "checking for $ac_word... " >&6; }
-if test ${ac_cv_prog_ac_ct_CC+y}
-then :
-  printf %s "(cached) " >&6
-else $as_nop
-  if test -n "$ac_ct_CC"; then
-  ac_cv_prog_ac_ct_CC="$ac_ct_CC" # Let the user override the test.
-else
-as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
-for as_dir in $PATH
-do
-  IFS=$as_save_IFS
-  case $as_dir in #(((
-    '') as_dir=./ ;;
-    */) ;;
-    *) as_dir=$as_dir/ ;;
-  esac
-    for ac_exec_ext in '' $ac_executable_extensions; do
-  if as_fn_executable_p "$as_dir$ac_word$ac_exec_ext"; then
-    ac_cv_prog_ac_ct_CC="gcc"
-    printf "%s\n" "$as_me:${as_lineno-$LINENO}: found $as_dir$ac_word$ac_exec_ext" >&5
-    break 2
-  fi
-done
-  done
-IFS=$as_save_IFS
-
-fi
-fi
-ac_ct_CC=$ac_cv_prog_ac_ct_CC
-if test -n "$ac_ct_CC"; then
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_ct_CC" >&5
-printf "%s\n" "$ac_ct_CC" >&6; }
-else
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: no" >&5
-printf "%s\n" "no" >&6; }
-fi
-
-  if test "x$ac_ct_CC" = x; then
-    CC=""
-  else
-    case $cross_compiling:$ac_tool_warned in
-yes:)
-{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: WARNING: using cross tools not prefixed with host triplet" >&5
-printf "%s\n" "$as_me: WARNING: using cross tools not prefixed with host triplet" >&2;}
-ac_tool_warned=yes ;;
-esac
-    CC=$ac_ct_CC
-  fi
-else
-  CC="$ac_cv_prog_CC"
-fi
-
-if test -z "$CC"; then
-          if test -n "$ac_tool_prefix"; then
-    # Extract the first word of "${ac_tool_prefix}cc", so it can be a program name with args.
-set dummy ${ac_tool_prefix}cc; ac_word=$2
-{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
-printf %s "checking for $ac_word... " >&6; }
-if test ${ac_cv_prog_CC+y}
-then :
-  printf %s "(cached) " >&6
-else $as_nop
-  if test -n "$CC"; then
-  ac_cv_prog_CC="$CC" # Let the user override the test.
-else
-as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
-for as_dir in $PATH
-do
-  IFS=$as_save_IFS
-  case $as_dir in #(((
-    '') as_dir=./ ;;
-    */) ;;
-    *) as_dir=$as_dir/ ;;
-  esac
-    for ac_exec_ext in '' $ac_executable_extensions; do
-  if as_fn_executable_p "$as_dir$ac_word$ac_exec_ext"; then
-    ac_cv_prog_CC="${ac_tool_prefix}cc"
-    printf "%s\n" "$as_me:${as_lineno-$LINENO}: found $as_dir$ac_word$ac_exec_ext" >&5
-    break 2
-  fi
-done
-  done
-IFS=$as_save_IFS
-
-fi
-fi
-CC=$ac_cv_prog_CC
-if test -n "$CC"; then
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $CC" >&5
-printf "%s\n" "$CC" >&6; }
-else
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: no" >&5
-printf "%s\n" "no" >&6; }
-fi
-
-
-  fi
-fi
-if test -z "$CC"; then
-  # Extract the first word of "cc", so it can be a program name with args.
-set dummy cc; ac_word=$2
-{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
-printf %s "checking for $ac_word... " >&6; }
-if test ${ac_cv_prog_CC+y}
-then :
-  printf %s "(cached) " >&6
-else $as_nop
-  if test -n "$CC"; then
-  ac_cv_prog_CC="$CC" # Let the user override the test.
-else
-  ac_prog_rejected=no
-as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
-for as_dir in $PATH
-do
-  IFS=$as_save_IFS
-  case $as_dir in #(((
-    '') as_dir=./ ;;
-    */) ;;
-    *) as_dir=$as_dir/ ;;
-  esac
-    for ac_exec_ext in '' $ac_executable_extensions; do
-  if as_fn_executable_p "$as_dir$ac_word$ac_exec_ext"; then
-    if test "$as_dir$ac_word$ac_exec_ext" = "/usr/ucb/cc"; then
-       ac_prog_rejected=yes
-       continue
-     fi
-    ac_cv_prog_CC="cc"
-    printf "%s\n" "$as_me:${as_lineno-$LINENO}: found $as_dir$ac_word$ac_exec_ext" >&5
-    break 2
-  fi
-done
-  done
-IFS=$as_save_IFS
-
-if test $ac_prog_rejected = yes; then
-  # We found a bogon in the path, so make sure we never use it.
-  set dummy $ac_cv_prog_CC
-  shift
-  if test $# != 0; then
-    # We chose a different compiler from the bogus one.
-    # However, it has the same basename, so the bogon will be chosen
-    # first if we set CC to just the basename; use the full file name.
-    shift
-    ac_cv_prog_CC="$as_dir$ac_word${1+' '}$@"
-  fi
-fi
-fi
-fi
-CC=$ac_cv_prog_CC
-if test -n "$CC"; then
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $CC" >&5
-printf "%s\n" "$CC" >&6; }
-else
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: no" >&5
-printf "%s\n" "no" >&6; }
-fi
-
-
-fi
-if test -z "$CC"; then
-  if test -n "$ac_tool_prefix"; then
-  for ac_prog in cl.exe
-  do
-    # Extract the first word of "$ac_tool_prefix$ac_prog", so it can be a program name with args.
-set dummy $ac_tool_prefix$ac_prog; ac_word=$2
-{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
-printf %s "checking for $ac_word... " >&6; }
-if test ${ac_cv_prog_CC+y}
-then :
-  printf %s "(cached) " >&6
-else $as_nop
-  if test -n "$CC"; then
-  ac_cv_prog_CC="$CC" # Let the user override the test.
-else
-as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
-for as_dir in $PATH
-do
-  IFS=$as_save_IFS
-  case $as_dir in #(((
-    '') as_dir=./ ;;
-    */) ;;
-    *) as_dir=$as_dir/ ;;
-  esac
-    for ac_exec_ext in '' $ac_executable_extensions; do
-  if as_fn_executable_p "$as_dir$ac_word$ac_exec_ext"; then
-    ac_cv_prog_CC="$ac_tool_prefix$ac_prog"
-    printf "%s\n" "$as_me:${as_lineno-$LINENO}: found $as_dir$ac_word$ac_exec_ext" >&5
-    break 2
-  fi
-done
-  done
-IFS=$as_save_IFS
-
-fi
-fi
-CC=$ac_cv_prog_CC
-if test -n "$CC"; then
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $CC" >&5
-printf "%s\n" "$CC" >&6; }
-else
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: no" >&5
-printf "%s\n" "no" >&6; }
-fi
-
-
-    test -n "$CC" && break
-  done
-fi
-if test -z "$CC"; then
-  ac_ct_CC=$CC
-  for ac_prog in cl.exe
-do
-  # Extract the first word of "$ac_prog", so it can be a program name with args.
-set dummy $ac_prog; ac_word=$2
-{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
-printf %s "checking for $ac_word... " >&6; }
-if test ${ac_cv_prog_ac_ct_CC+y}
-then :
-  printf %s "(cached) " >&6
-else $as_nop
-  if test -n "$ac_ct_CC"; then
-  ac_cv_prog_ac_ct_CC="$ac_ct_CC" # Let the user override the test.
-else
-as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
-for as_dir in $PATH
-do
-  IFS=$as_save_IFS
-  case $as_dir in #(((
-    '') as_dir=./ ;;
-    */) ;;
-    *) as_dir=$as_dir/ ;;
-  esac
-    for ac_exec_ext in '' $ac_executable_extensions; do
-  if as_fn_executable_p "$as_dir$ac_word$ac_exec_ext"; then
-    ac_cv_prog_ac_ct_CC="$ac_prog"
-    printf "%s\n" "$as_me:${as_lineno-$LINENO}: found $as_dir$ac_word$ac_exec_ext" >&5
-    break 2
-  fi
-done
-  done
-IFS=$as_save_IFS
-
-fi
-fi
-ac_ct_CC=$ac_cv_prog_ac_ct_CC
-if test -n "$ac_ct_CC"; then
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_ct_CC" >&5
-printf "%s\n" "$ac_ct_CC" >&6; }
-else
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: no" >&5
-printf "%s\n" "no" >&6; }
-fi
-
-
-  test -n "$ac_ct_CC" && break
-done
-
-  if test "x$ac_ct_CC" = x; then
-    CC=""
-  else
-    case $cross_compiling:$ac_tool_warned in
-yes:)
-{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: WARNING: using cross tools not prefixed with host triplet" >&5
-printf "%s\n" "$as_me: WARNING: using cross tools not prefixed with host triplet" >&2;}
-ac_tool_warned=yes ;;
-esac
-    CC=$ac_ct_CC
-  fi
-fi
-
-fi
-if test -z "$CC"; then
-  if test -n "$ac_tool_prefix"; then
-  # Extract the first word of "${ac_tool_prefix}clang", so it can be a program name with args.
-set dummy ${ac_tool_prefix}clang; ac_word=$2
-{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
-printf %s "checking for $ac_word... " >&6; }
-if test ${ac_cv_prog_CC+y}
-then :
-  printf %s "(cached) " >&6
-else $as_nop
-  if test -n "$CC"; then
-  ac_cv_prog_CC="$CC" # Let the user override the test.
-else
-as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
-for as_dir in $PATH
-do
-  IFS=$as_save_IFS
-  case $as_dir in #(((
-    '') as_dir=./ ;;
-    */) ;;
-    *) as_dir=$as_dir/ ;;
-  esac
-    for ac_exec_ext in '' $ac_executable_extensions; do
-  if as_fn_executable_p "$as_dir$ac_word$ac_exec_ext"; then
-    ac_cv_prog_CC="${ac_tool_prefix}clang"
-    printf "%s\n" "$as_me:${as_lineno-$LINENO}: found $as_dir$ac_word$ac_exec_ext" >&5
-    break 2
-  fi
-done
-  done
-IFS=$as_save_IFS
-
-fi
-fi
-CC=$ac_cv_prog_CC
-if test -n "$CC"; then
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $CC" >&5
-printf "%s\n" "$CC" >&6; }
-else
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: no" >&5
-printf "%s\n" "no" >&6; }
-fi
-
-
-fi
-if test -z "$ac_cv_prog_CC"; then
-  ac_ct_CC=$CC
-  # Extract the first word of "clang", so it can be a program name with args.
-set dummy clang; ac_word=$2
-{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
-printf %s "checking for $ac_word... " >&6; }
-if test ${ac_cv_prog_ac_ct_CC+y}
-then :
-  printf %s "(cached) " >&6
-else $as_nop
-  if test -n "$ac_ct_CC"; then
-  ac_cv_prog_ac_ct_CC="$ac_ct_CC" # Let the user override the test.
-else
-as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
-for as_dir in $PATH
-do
-  IFS=$as_save_IFS
-  case $as_dir in #(((
-    '') as_dir=./ ;;
-    */) ;;
-    *) as_dir=$as_dir/ ;;
-  esac
-    for ac_exec_ext in '' $ac_executable_extensions; do
-  if as_fn_executable_p "$as_dir$ac_word$ac_exec_ext"; then
-    ac_cv_prog_ac_ct_CC="clang"
-    printf "%s\n" "$as_me:${as_lineno-$LINENO}: found $as_dir$ac_word$ac_exec_ext" >&5
-    break 2
-  fi
-done
-  done
-IFS=$as_save_IFS
-
-fi
-fi
-ac_ct_CC=$ac_cv_prog_ac_ct_CC
-if test -n "$ac_ct_CC"; then
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_ct_CC" >&5
-printf "%s\n" "$ac_ct_CC" >&6; }
-else
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: no" >&5
-printf "%s\n" "no" >&6; }
-fi
-
-  if test "x$ac_ct_CC" = x; then
-    CC=""
-  else
-    case $cross_compiling:$ac_tool_warned in
-yes:)
-{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: WARNING: using cross tools not prefixed with host triplet" >&5
-printf "%s\n" "$as_me: WARNING: using cross tools not prefixed with host triplet" >&2;}
-ac_tool_warned=yes ;;
-esac
-    CC=$ac_ct_CC
-  fi
-else
-  CC="$ac_cv_prog_CC"
-fi
-
-fi
-
-
-test -z "$CC" && { { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
-printf "%s\n" "$as_me: error: in \`$ac_pwd':" >&2;}
-as_fn_error $? "no acceptable C compiler found in \$PATH
-See \`config.log' for more details" "$LINENO" 5; }
-
-# Provide some information about the compiler.
-printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for C compiler version" >&5
-set X $ac_compile
-ac_compiler=$2
-for ac_option in --version -v -V -qversion -version; do
-  { { ac_try="$ac_compiler $ac_option >&5"
-case "(($ac_try" in
-  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
-  *) ac_try_echo=$ac_try;;
-esac
-eval ac_try_echo="\"\$as_me:${as_lineno-$LINENO}: $ac_try_echo\""
-printf "%s\n" "$ac_try_echo"; } >&5
-  (eval "$ac_compiler $ac_option >&5") 2>conftest.err
-  ac_status=$?
-  if test -s conftest.err; then
-    sed '10a\
-... rest of stderr output deleted ...
-         10q' conftest.err >conftest.er1
-    cat conftest.er1 >&5
-  fi
-  rm -f conftest.er1 conftest.err
-  printf "%s\n" "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
-  test $ac_status = 0; }
-done
-
-{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking whether the compiler supports GNU C" >&5
-printf %s "checking whether the compiler supports GNU C... " >&6; }
-if test ${ac_cv_c_compiler_gnu+y}
-then :
-  printf %s "(cached) " >&6
-else $as_nop
-  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-
-int
-main (void)
-{
-#ifndef __GNUC__
-       choke me
-#endif
-
-  ;
-  return 0;
-}
-_ACEOF
-if ac_fn_c_try_compile "$LINENO"
-then :
-  ac_compiler_gnu=yes
-else $as_nop
-  ac_compiler_gnu=no
-fi
-rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext
-ac_cv_c_compiler_gnu=$ac_compiler_gnu
-
-fi
-{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_c_compiler_gnu" >&5
-printf "%s\n" "$ac_cv_c_compiler_gnu" >&6; }
-ac_compiler_gnu=$ac_cv_c_compiler_gnu
-
-if test $ac_compiler_gnu = yes; then
-  GCC=yes
-else
-  GCC=
-fi
-ac_test_CFLAGS=${CFLAGS+y}
-ac_save_CFLAGS=$CFLAGS
-{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking whether $CC accepts -g" >&5
-printf %s "checking whether $CC accepts -g... " >&6; }
-if test ${ac_cv_prog_cc_g+y}
-then :
-  printf %s "(cached) " >&6
-else $as_nop
-  ac_save_c_werror_flag=$ac_c_werror_flag
-   ac_c_werror_flag=yes
-   ac_cv_prog_cc_g=no
-   CFLAGS="-g"
-   cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-
-int
-main (void)
-{
-
-  ;
-  return 0;
-}
-_ACEOF
-if ac_fn_c_try_compile "$LINENO"
-then :
-  ac_cv_prog_cc_g=yes
-else $as_nop
-  CFLAGS=""
-      cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-
-int
-main (void)
-{
-
-  ;
-  return 0;
-}
-_ACEOF
-if ac_fn_c_try_compile "$LINENO"
-then :
-
-else $as_nop
-  ac_c_werror_flag=$ac_save_c_werror_flag
-	 CFLAGS="-g"
-	 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-
-int
-main (void)
-{
-
-  ;
-  return 0;
-}
-_ACEOF
-if ac_fn_c_try_compile "$LINENO"
-then :
-  ac_cv_prog_cc_g=yes
-fi
-rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext
-fi
-rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext
-fi
-rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext
-   ac_c_werror_flag=$ac_save_c_werror_flag
-fi
-{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_prog_cc_g" >&5
-printf "%s\n" "$ac_cv_prog_cc_g" >&6; }
-if test $ac_test_CFLAGS; then
-  CFLAGS=$ac_save_CFLAGS
-elif test $ac_cv_prog_cc_g = yes; then
-  if test "$GCC" = yes; then
-    CFLAGS="-g -O2"
-  else
-    CFLAGS="-g"
-  fi
-else
-  if test "$GCC" = yes; then
-    CFLAGS="-O2"
-  else
-    CFLAGS=
-  fi
-fi
-ac_prog_cc_stdc=no
-if test x$ac_prog_cc_stdc = xno
-then :
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for $CC option to enable C11 features" >&5
-printf %s "checking for $CC option to enable C11 features... " >&6; }
-if test ${ac_cv_prog_cc_c11+y}
-then :
-  printf %s "(cached) " >&6
-else $as_nop
-  ac_cv_prog_cc_c11=no
-ac_save_CC=$CC
-cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-$ac_c_conftest_c11_program
-_ACEOF
-for ac_arg in '' -std=gnu11
-do
-  CC="$ac_save_CC $ac_arg"
-  if ac_fn_c_try_compile "$LINENO"
-then :
-  ac_cv_prog_cc_c11=$ac_arg
-fi
-rm -f core conftest.err conftest.$ac_objext conftest.beam
-  test "x$ac_cv_prog_cc_c11" != "xno" && break
-done
-rm -f conftest.$ac_ext
-CC=$ac_save_CC
-fi
-
-if test "x$ac_cv_prog_cc_c11" = xno
-then :
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: unsupported" >&5
-printf "%s\n" "unsupported" >&6; }
-else $as_nop
-  if test "x$ac_cv_prog_cc_c11" = x
-then :
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: none needed" >&5
-printf "%s\n" "none needed" >&6; }
-else $as_nop
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_prog_cc_c11" >&5
-printf "%s\n" "$ac_cv_prog_cc_c11" >&6; }
-     CC="$CC $ac_cv_prog_cc_c11"
-fi
-  ac_cv_prog_cc_stdc=$ac_cv_prog_cc_c11
-  ac_prog_cc_stdc=c11
-fi
-fi
-if test x$ac_prog_cc_stdc = xno
-then :
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for $CC option to enable C99 features" >&5
-printf %s "checking for $CC option to enable C99 features... " >&6; }
-if test ${ac_cv_prog_cc_c99+y}
-then :
-  printf %s "(cached) " >&6
-else $as_nop
-  ac_cv_prog_cc_c99=no
-ac_save_CC=$CC
-cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-$ac_c_conftest_c99_program
-_ACEOF
-for ac_arg in '' -std=gnu99 -std=c99 -c99 -qlanglvl=extc1x -qlanglvl=extc99 -AC99 -D_STDC_C99=
-do
-  CC="$ac_save_CC $ac_arg"
-  if ac_fn_c_try_compile "$LINENO"
-then :
-  ac_cv_prog_cc_c99=$ac_arg
-fi
-rm -f core conftest.err conftest.$ac_objext conftest.beam
-  test "x$ac_cv_prog_cc_c99" != "xno" && break
-done
-rm -f conftest.$ac_ext
-CC=$ac_save_CC
-fi
-
-if test "x$ac_cv_prog_cc_c99" = xno
-then :
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: unsupported" >&5
-printf "%s\n" "unsupported" >&6; }
-else $as_nop
-  if test "x$ac_cv_prog_cc_c99" = x
-then :
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: none needed" >&5
-printf "%s\n" "none needed" >&6; }
-else $as_nop
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_prog_cc_c99" >&5
-printf "%s\n" "$ac_cv_prog_cc_c99" >&6; }
-     CC="$CC $ac_cv_prog_cc_c99"
-fi
-  ac_cv_prog_cc_stdc=$ac_cv_prog_cc_c99
-  ac_prog_cc_stdc=c99
-fi
-fi
-if test x$ac_prog_cc_stdc = xno
-then :
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for $CC option to enable C89 features" >&5
-printf %s "checking for $CC option to enable C89 features... " >&6; }
-if test ${ac_cv_prog_cc_c89+y}
-then :
-  printf %s "(cached) " >&6
-else $as_nop
-  ac_cv_prog_cc_c89=no
-ac_save_CC=$CC
-cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-$ac_c_conftest_c89_program
-_ACEOF
-for ac_arg in '' -qlanglvl=extc89 -qlanglvl=ansi -std -Ae "-Aa -D_HPUX_SOURCE" "-Xc -D__EXTENSIONS__"
-do
-  CC="$ac_save_CC $ac_arg"
-  if ac_fn_c_try_compile "$LINENO"
-then :
-  ac_cv_prog_cc_c89=$ac_arg
-fi
-rm -f core conftest.err conftest.$ac_objext conftest.beam
-  test "x$ac_cv_prog_cc_c89" != "xno" && break
-done
-rm -f conftest.$ac_ext
-CC=$ac_save_CC
-fi
-
-if test "x$ac_cv_prog_cc_c89" = xno
-then :
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: unsupported" >&5
-printf "%s\n" "unsupported" >&6; }
-else $as_nop
-  if test "x$ac_cv_prog_cc_c89" = x
-then :
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: none needed" >&5
-printf "%s\n" "none needed" >&6; }
-else $as_nop
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_prog_cc_c89" >&5
-printf "%s\n" "$ac_cv_prog_cc_c89" >&6; }
-     CC="$CC $ac_cv_prog_cc_c89"
-fi
-  ac_cv_prog_cc_stdc=$ac_cv_prog_cc_c89
-  ac_prog_cc_stdc=c89
-fi
-fi
-
-ac_ext=c
-ac_cpp='$CPP $CPPFLAGS'
-ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5'
-ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
-ac_compiler_gnu=$ac_cv_c_compiler_gnu
-
-
-
-  # Find a good install program.  We prefer a C program (faster),
-# so one script is as good as another.  But avoid the broken or
-# incompatible versions:
-# SysV /etc/install, /usr/sbin/install
-# SunOS /usr/etc/install
-# IRIX /sbin/install
-# AIX /bin/install
-# AmigaOS /C/install, which installs bootblocks on floppy discs
-# AIX 4 /usr/bin/installbsd, which doesn't work without a -g flag
-# AFS /usr/afsws/bin/install, which mishandles nonexistent args
-# SVR4 /usr/ucb/install, which tries to use the nonexistent group "staff"
-# OS/2's system install, which has a completely different semantic
-# ./install, which can be erroneously created by make from ./install.sh.
-# Reject install programs that cannot install multiple files.
-{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for a BSD-compatible install" >&5
-printf %s "checking for a BSD-compatible install... " >&6; }
-if test -z "$INSTALL"; then
-if test ${ac_cv_path_install+y}
-then :
-  printf %s "(cached) " >&6
-else $as_nop
-  as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
-for as_dir in $PATH
-do
-  IFS=$as_save_IFS
-  case $as_dir in #(((
-    '') as_dir=./ ;;
-    */) ;;
-    *) as_dir=$as_dir/ ;;
-  esac
-    # Account for fact that we put trailing slashes in our PATH walk.
-case $as_dir in #((
-  ./ | /[cC]/* | \
-  /etc/* | /usr/sbin/* | /usr/etc/* | /sbin/* | /usr/afsws/bin/* | \
-  ?:[\\/]os2[\\/]install[\\/]* | ?:[\\/]OS2[\\/]INSTALL[\\/]* | \
-  /usr/ucb/* ) ;;
-  *)
-    # OSF1 and SCO ODT 3.0 have their own names for install.
-    # Don't use installbsd from OSF since it installs stuff as root
-    # by default.
-    for ac_prog in ginstall scoinst install; do
-      for ac_exec_ext in '' $ac_executable_extensions; do
-	if as_fn_executable_p "$as_dir$ac_prog$ac_exec_ext"; then
-	  if test $ac_prog = install &&
-	    grep dspmsg "$as_dir$ac_prog$ac_exec_ext" >/dev/null 2>&1; then
-	    # AIX install.  It has an incompatible calling convention.
-	    :
-	  elif test $ac_prog = install &&
-	    grep pwplus "$as_dir$ac_prog$ac_exec_ext" >/dev/null 2>&1; then
-	    # program-specific install script used by HP pwplus--don't use.
-	    :
-	  else
-	    rm -rf conftest.one conftest.two conftest.dir
-	    echo one > conftest.one
-	    echo two > conftest.two
-	    mkdir conftest.dir
-	    if "$as_dir$ac_prog$ac_exec_ext" -c conftest.one conftest.two "`pwd`/conftest.dir/" &&
-	      test -s conftest.one && test -s conftest.two &&
-	      test -s conftest.dir/conftest.one &&
-	      test -s conftest.dir/conftest.two
-	    then
-	      ac_cv_path_install="$as_dir$ac_prog$ac_exec_ext -c"
-	      break 3
-	    fi
-	  fi
-	fi
-      done
-    done
-    ;;
-esac
-
-  done
-IFS=$as_save_IFS
-
-rm -rf conftest.one conftest.two conftest.dir
-
-fi
-  if test ${ac_cv_path_install+y}; then
-    INSTALL=$ac_cv_path_install
-  else
-    # As a last resort, use the slow shell script.  Don't cache a
-    # value for INSTALL within a source directory, because that will
-    # break other packages using the cache if that directory is
-    # removed, or if the value is a relative name.
-    INSTALL=$ac_install_sh
-  fi
-fi
-{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $INSTALL" >&5
-printf "%s\n" "$INSTALL" >&6; }
-
-# Use test -z because SunOS4 sh mishandles braces in ${var-val}.
-# It thinks the first close brace ends the variable substitution.
-test -z "$INSTALL_PROGRAM" && INSTALL_PROGRAM='${INSTALL}'
-
-test -z "$INSTALL_SCRIPT" && INSTALL_SCRIPT='${INSTALL}'
-
-test -z "$INSTALL_DATA" && INSTALL_DATA='${INSTALL} -m 644'
-
-
 ac_config_files="$ac_config_files Makefile src/Makefile src/audio/Makefile"
 
 
diff --git a/configure.ac b/configure.ac
index 813a6b3..188fce0 100644
--- a/configure.ac
+++ b/configure.ac
@@ -4,6 +4,51 @@ AC_CONFIG_SRCDIR([src/cpu6502.c])
 
 AC_CONFIG_HEADERS([src/config.h])
 
+# Checks for programs.
+AC_PROG_CC
+AC_PROG_INSTALL
+
+# User-specified SDL2 path.
+AC_ARG_WITH([sdl-prefix],
+  [AS_HELP_STRING([--with-sdl-prefix=DIR],
+                  [Specify the prefix directory for SDL2])],
+  [sdl_prefix=$withval],
+  [sdl_prefix=""])
+
+if test -n "$sdl_prefix"; then
+  CFLAGS="$CFLAGS -I$sdl_prefix/include"
+  LDFLAGS="$LDFLAGS -L$sdl_prefix/lib"
+fi
+
+# User-specified SDL2_ttf path.
+AC_ARG_WITH([sdl-ttf-prefix],
+  [AS_HELP_STRING([--with-sdl-ttf-prefix=DIR],
+                  [Specify the prefix directory for SDL2_ttf])],
+  [sdl_ttf_prefix=$withval],
+  [sdl_ttf_prefix=""])
+
+if test -n "$sdl_ttf_prefix"; then
+  CFLAGS="$CFLAGS -I$sdl_ttf_prefix/include/SDL2"
+  LDFLAGS="$LDFLAGS -L$sdl_ttf_prefix/lib"
+fi
+
+# Validate SDL2 installation.
+AC_CHECK_HEADER([SDL2/SDL_ttf.h],
+  [AC_MSG_NOTICE([SDL2_ttf headers found])],
+  [AC_MSG_ERROR([SDL2_ttf headers not found in $sdl2_ttf_prefix/include/SDL2])])
+
+AC_CHECK_LIB([SDL2_ttf], [TTF_Init],
+  [AC_MSG_NOTICE([SDL2_ttf library found])],
+  [AC_MSG_ERROR([SDL2_ttf library not found in $sdl2_ttf_prefix/lib])])
+
+AC_CHECK_HEADER([SDL2/SDL.h],
+  [AC_MSG_NOTICE([SDL2 headers found])],
+  [AC_MSG_ERROR([SDL2 headers not found in $sdl2_prefix/include/SDL2])])
+
+AC_CHECK_LIB([SDL2], [SDL_Init],
+  [AC_MSG_NOTICE([SDL2 library found])],
+  [AC_MSG_ERROR([SDL2 library not found in $sdl2_prefix/lib])])
+
 # Checks for header files.
 AC_CHECK_HEADERS([
         stdlib.h stdint.h time.h
@@ -11,10 +56,6 @@ AC_CHECK_HEADERS([
         stdarg.h stdio.h
         ])
 
-# Checks for programs.
-AC_PROG_CC
-AC_PROG_INSTALL
-
 AC_CONFIG_FILES([
         Makefile
         src/Makefile
diff --git a/src/Makefile.in b/src/Makefile.in
index 5cb22c3..df0d0ef 100644
--- a/src/Makefile.in
+++ b/src/Makefile.in
@@ -14,7 +14,7 @@ bindir      = @bindir@
 # Build-specific substitution variables.
 CC      = @CC@
 CFLAGS  = @CFLAGS@ -Wall -O0 -I.
-LDFLAGS = -lm -lSDL2 -lSDL2_ttf
+LDFLAGS = @LDFLAGS@ -lm -lSDL2 -lSDL2_ttf
 
 # Install script substitution variables.
 INSTALL         = @INSTALL@
@@ -33,7 +33,7 @@ TARGET = nes-tools
 all: $(TARGET)
 
 $(TARGET): $(AUDIO_OBJ_FILES) $(OBJ_FILES)
-	$(CC) $(CFLAGS) -o $@ $^ $(LDFLAGS)
+	$(CC) $(CFLAGS) $(LDFLAGS) -o $@ $^
 
 $(AUDIO_OBJ_FILES): $(AUDIO_SRC_FILES) $(AUDIO_HDR_FILES)
 	$(MAKE) -C $(AUDIO_DIR) all