1 files changed, 1 insertions, 1 deletions
diff --git a/lib/ASN1.y b/lib/ASN1.y
index 174ffde..534a9f1 100644
--- a/lib/ASN1.y
+++ b/lib/ASN1.y
@@ -575,7 +575,7 @@ _asn1_yylex ()
 
       /* Is STRING a number? */
       for (k = 0; k < counter; k++)
-        if (!isdigit (string[k]))
+        if (!isdigit ((int)string[k]))
           break;
       if (k >= counter)
         {