diff --git a/src/tokenize.c b/src/tokenize.c
index 3e6b53f1..47411b23 100644
--- a/src/tokenize.c
+++ b/src/tokenize.c
@@ -45,7 +45,7 @@ static char read_byte(struct State *st) {
 
     // Use the zero byte to represent end of file.
     if (c == '\0')
-        fail_with_error(st->location, "source file contains a zero byte");  // TODO: test this
+        fail_with_error(st->location, "source file contains a zero byte");
     if (c == EOF) {
         assert(!ferror(st->f));
         return '\0';
@@ -220,9 +220,10 @@ static bool is_keyword(const char *s)
         //   - self-hosted compiler
         //   - syntax documentation
         "import", "def", "declare", "class", "union", "enum", "global",
-        "return", "if", "elif", "else", "while", "for", "pass", "break", "continue",
-        "True", "False", "None", "NULL", "void", "noreturn",
-        "and", "or", "not", "self", "as", "sizeof", "assert",
+        "return", "if", "elif", "else", "while", "for", "break", "continue",
+        "True", "False", "NULL", "self",
+        "and", "or", "not", "as", "sizeof", "assert", "pass",
+        "void", "noreturn",
         "bool", "byte", "short", "int", "long", "float", "double",
     };
     for (const char **kw = &keywords[0]; kw < &keywords[sizeof(keywords)/sizeof(keywords[0])]; kw++)
@@ -295,7 +296,6 @@ static char *read_string(struct State *st, char quote, int *len)
             case '\n':
                 // \ at end of line, string continues on next line
                 if (quote == '\'') {
-                    // TODO: tests
                     st->location.lineno--;  // to get error at the correct line number
                     goto missing_end_quote;
                 }
@@ -321,7 +321,6 @@ static char *read_string(struct State *st, char quote, int *len)
     return result.ptr;
 
 missing_end_quote:
-    // TODO: tests
     if (quote == '"')
         fail_with_error(st->location, "missing \" to end the string");
     else
diff --git a/tests/other_errors/source_file_contain_zero_byte.jou b/tests/other_errors/source_file_contain_zero_byte.jou
new file mode 100644
index 00000000..c8259c7c
Binary files /dev/null and b/tests/other_errors/source_file_contain_zero_byte.jou differ
diff --git a/tests/syntax_error/missing_end_quote_in_byte.jou b/tests/syntax_error/missing_end_quote_in_byte.jou
new file mode 100644
index 00000000..52fe3caf
--- /dev/null
+++ b/tests/syntax_error/missing_end_quote_in_byte.jou
@@ -0,0 +1,6 @@
+import "stdlib/io.jou"
+
+# Output: compiler error in file "tests/syntax_error/missing_end_quote_in_byte.jou", line 5: missing ' to end the byte literal
+def main() -> int:
+    printf('?) 
+    return 0
diff --git a/tests/syntax_error/missing_end_quote_in_string.jou b/tests/syntax_error/missing_end_quote_in_string.jou
new file mode 100644
index 00000000..a860da4c
--- /dev/null
+++ b/tests/syntax_error/missing_end_quote_in_string.jou
@@ -0,0 +1,6 @@
+import "stdlib/io.jou"
+
+# Output: compiler error in file "tests/syntax_error/missing_end_quote_in_string.jou", line 5: missing " to end the string
+def main() -> int:
+    printf("Hello) 
+    return 0
diff --git a/tests/syntax_error/string_continue_on_next_line.jou b/tests/syntax_error/string_continue_on_next_line.jou
new file mode 100644
index 00000000..c9fc5d5d
--- /dev/null
+++ b/tests/syntax_error/string_continue_on_next_line.jou
@@ -0,0 +1,8 @@
+import "stdlib/io.jou"
+
+# Output: compiler error in file "tests/syntax_error/string_continue_on_next_line.jou", line 5: missing ' to end the byte literal
+def main() -> int:
+    a = '\
+    't\''
+    printf(a)
+    return 0