diff --git a/lib/crypto/c_src/crypto_callback.c b/lib/crypto/c_src/crypto_callback.c
index 53b4bbf1e0a7..e62bc17d4072 100644
--- a/lib/crypto/c_src/crypto_callback.c
+++ b/lib/crypto/c_src/crypto_callback.c
@@ -231,11 +231,10 @@ DLLEXPORT struct crypto_callbacks* get_crypto_callbacks(int nlocks)
 #ifdef HAVE_DYNAMIC_CRYPTO_LIB
 /* This is not really a NIF library, but we use ERL_NIF_INIT in order to
  * get access to the erl_nif API (on Windows).
+ *
+ * Unused 'dummy_funcv' has size 1 to avoid warning "sizeof returns 0".
  */
-static struct {
-    int dummy__;
-    ErlNifFunc funcv[0];
-} empty;
-ERL_NIF_INIT(dummy, empty.funcv, NULL, NULL, NULL, NULL)
+ErlNifFunc dummy_funcv[1];
+ERL_NIF_INIT(dummy, dummy_funcv, NULL, NULL, NULL, NULL)
 #endif
 
diff --git a/lib/erl_interface/src/prog/erl_call.c b/lib/erl_interface/src/prog/erl_call.c
index 6ce6ed1c732a..74750d78de8e 100644
--- a/lib/erl_interface/src/prog/erl_call.c
+++ b/lib/erl_interface/src/prog/erl_call.c
@@ -976,7 +976,7 @@ static DWORD WINAPI timer_thread(void *data) {
 }
 
 static void start_timeout(int timeout) {
-    if (CreateThread(NULL, 0, timer_thread, (void*)timeout, 0, NULL) == NULL) {
+    if (CreateThread(NULL, 0, timer_thread, (void*)(DWORD_PTR)timeout, 0, NULL) == NULL) {
         fprintf(stderr,"erl_call: Failed to start timer thread\n");
         exit(1);
     }
diff --git a/lib/os_mon/c_src/win32sysinfo.c b/lib/os_mon/c_src/win32sysinfo.c
index 85622e00760d..bd51bf6777fb 100644
--- a/lib/os_mon/c_src/win32sysinfo.c
+++ b/lib/os_mon/c_src/win32sysinfo.c
@@ -150,7 +150,9 @@ void output_drive_info(char* drive){
 	    }
 	    else
 		if (fpGetDiskFreeSpaceEx(drive,&availbytes,&totbytes,&totbytesfree)){
-		    sprintf(answer,"%s DRIVE_FIXED %I64u %I64u %I64u\n",drive,availbytes,totbytes,totbytesfree);
+		    sprintf(answer,"%s DRIVE_FIXED %I64u %I64u %I64u\n",
+                            drive, availbytes.QuadPart, totbytes.QuadPart,
+                            totbytesfree.QuadPart);
 		    return_answer(answer);
 		}
 		else {
diff --git a/lib/runtime_tools/c_src/trace_ip_drv.c b/lib/runtime_tools/c_src/trace_ip_drv.c
index c6f42b3b5256..1774657d1001 100644
--- a/lib/runtime_tools/c_src/trace_ip_drv.c
+++ b/lib/runtime_tools/c_src/trace_ip_drv.c
@@ -50,8 +50,13 @@
 #    define ASSERT(X)
 #endif 
 
-#define sock2event(s) ((ErlDrvEvent)(long)(s))
-#define event2sock(p) ((SOCKET)(long)(p))
+#ifdef __WIN32__
+# define sock2event(s) ((ErlDrvEvent)(INT_PTR)(s))
+# define event2sock(p) ((SOCKET)(INT_PTR)(p))
+#else
+# define sock2event(s) ((ErlDrvEvent)(long)(s))
+# define event2sock(p) ((SOCKET)(long)(p))
+#endif
 
 #include "erl_driver.h"
 
@@ -432,7 +437,7 @@ static void trace_ip_ready_input(ErlDrvData handle, ErlDrvEvent fd)
      * but better make sure.
      */
 
-    if ((SOCKET)(long)fd == data->fd) {
+    if (event2sock(fd) == data->fd) {
 #ifdef __WIN32__
 	close_client(data);
 #else
@@ -496,7 +501,7 @@ static void trace_ip_ready_output(ErlDrvData handle, ErlDrvEvent fd)
 
     ASSERT(!(data->flags & FLAG_LISTEN_PORT) &&
 	   data->que[data->questart] != NULL &&
-	   (SOCKET)(long)fd == data->fd);
+	   event2sock(fd) == data->fd);
     
     tim = data->que[data->questart];
     towrite = tim->siz - tim->written;
@@ -906,7 +911,7 @@ static int my_driver_select(TraceIpData *desc, SOCKET fd, int flags, enum MySele
 
 static void stop_select(ErlDrvEvent event, void* _)
 {
-    closesocket((SOCKET)(long)event);
+    closesocket(event2sock(event));
 }
 
 #endif /* !__WIN32__ */