fix improper sign extension

1 files changed, 1 insertions, 1 deletions

diff --git a/zwgc/character_class.c b/zwgc/character_class.c
index 2f3c433..7f81347 100644
--- a/zwgc/character_class.c
+++ b/zwgc/character_class.c
@@ -37,7 +37,7 @@ string_to_character_class(string str)
     (void) memset(cache, 0, sizeof(cache));
 
     for (i=0; i<strlen(str); i++)
-	cache[(int)str[i]] = 1;
+	cache[(int)(unsigned char)str[i]] = 1;
 
     return(cache);
 }