1 files changed, 1 insertions, 0 deletions
diff --git a/sprintf.c b/sprintf.c
index 74229cc2d7..0d685ddbaf 100644
--- a/sprintf.c
+++ b/sprintf.c
@@ -648,6 +648,7 @@ rb_str_format(int argc, const VALUE *argv, VALUE fmt)
 	    if (width < 0) {
 		flags |= FMINUS;
 		width = -width;
+		if (width < 0) rb_raise(rb_eArgError, "width too big");
 	    }
 	    p++;
 	    goto retry;