Arguments to ctype functions are required to be either EOF or representable

[u/mdw/putty] / cmdgen.c

diff --git a/cmdgen.c b/cmdgen.c
index 9aa585f..ae40520 100644 (file)
--- a/cmdgen.c
+++ b/cmdgen.c
@@ -119,7 +119,7 @@ void sk_cleanup(void)
 void showversion(void)
 {
     char *verstr = dupstr(ver);
-    verstr[0] = tolower(verstr[0]);
+    verstr[0] = tolower((unsigned char)verstr[0]);
     printf("PuTTYgen %s\n", verstr);
     sfree(verstr);
 }