diff --git a/Parser/grammar.c b/Parser/grammar.c
index c0613df..d8e3897 100644
--- a/Parser/grammar.c
+++ b/Parser/grammar.c
@@ -180,7 +180,8 @@
 	}
 	
 	if (lb->lb_type == STRING) {
-		if (isalpha((int)(lb->lb_str[1])) || lb->lb_str[1] == '_') {
+		if (isalpha(Py_CHARMASK(lb->lb_str[1])) ||
+		    lb->lb_str[1] == '_') {
 			char *p;
 			char *src;
 			char *dest;
diff --git a/Parser/tokenizer.c b/Parser/tokenizer.c
index a79ea81..3b1d6a6 100644
--- a/Parser/tokenizer.c
+++ b/Parser/tokenizer.c
@@ -229,7 +229,7 @@
 			} while (t[0] == '\x20' || t[0] == '\t');
 
 			begin = t;
-			while (isalnum((int)t[0]) ||
+			while (isalnum(Py_CHARMASK(t[0])) ||
 			       t[0] == '-' || t[0] == '_' || t[0] == '.')
 				t++;