diff --git a/xyntax.c b/xyntax.c
index 487f425..764b8f7 100644
--- a/xyntax.c
+++ b/xyntax.c
@@ -150,16 +150,20 @@ void syntax_define_default (int string_colour, int string_effect, int number_col
 	(void) syntax_insert (1, 1, "0123456789", syntax_separator, '\0', number_colour, number_effect);
 }
 
-void syntax_define_words (char * * word_array, int word_count, int word_colour, int word_effect) {
+void syntax_define_words (int case_sensitive, char * * word_array, int word_count, int word_colour, int word_effect) {
 	int word = 0;
 
 	for (word = 0; word != word_count; ++word) {
 		(void) syntax_insert (0, 1, word_array [word], syntax_separator, '\0', word_colour, word_effect);
 	}
 
-	(void) syntax_insert (1, 1, "abcdefghijklmnopqrstuvwxyz", syntax_separator, '\0', COLOUR_WHITE, EFFECT_NORMAL);
-	(void) syntax_insert (1, 1, "ABCDEFGHIJKLMNOPQRSTUVWXYZ", syntax_separator, '\0', COLOUR_WHITE, EFFECT_BOLD);
-	(void) syntax_insert (1, 1, "_",                          syntax_separator, '\0', COLOUR_PINK,  EFFECT_BOLD);
+	if (case_sensitive != 0) {
+		(void) syntax_insert (1, 1, "abcdefghijklmnopqrstuvwxyz", syntax_separator, '\0', COLOUR_WHITE, EFFECT_NORMAL);
+		(void) syntax_insert (1, 1, "ABCDEFGHIJKLMNOPQRSTUVWXYZ", syntax_separator, '\0', COLOUR_WHITE, EFFECT_BOLD);
+		(void) syntax_insert (1, 1, "_",                          syntax_separator, '\0', COLOUR_PINK,  EFFECT_BOLD);
+	} else {
+		(void) syntax_insert (1, 1, "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_", syntax_separator, '\0', COLOUR_WHITE, EFFECT_NORMAL);
+	}
 }
 
 void syntax_define_range (char * range_begin, char * range_end, char range_escape, int range_colour, int range_effect) {
diff --git a/xyntax.h b/xyntax.h
index 8edda8f..04666af 100644
--- a/xyntax.h
+++ b/xyntax.h
@@ -36,7 +36,7 @@ extern void syntax_define_separators (char *);
 
 extern void syntax_define_default (int, int, int, int);
 
-extern void syntax_define_words (char * *, int, int, int);
+extern void syntax_define_words (int, char * *, int, int, int);
 
 extern void syntax_define_range (char *, char *, char, int, int);