1 files changed, 1 insertions, 1 deletions
diff --git a/ext/syck/token.c b/ext/syck/token.c
index 0d0d4846ba..3d05527e65 100644
--- a/ext/syck/token.c
+++ b/ext/syck/token.c
@@ -2361,7 +2361,7 @@ ScalarBlock:
             {
                 nlDoWhat = NL_KEEP;
             }
-            else if ( isdigit( *yyt ) )
+            else if ( isdigit( (unsigned char)*yyt ) )
             {
                 forceIndent = rb_long2int(strtol( yyt, NULL, 10 ));
             }