1 files changed, 1 insertions, 1 deletions
diff --git a/sprintf.c b/sprintf.c
index 5c1f7780f0..d67ffff08c 100644
--- a/sprintf.c
+++ b/sprintf.c
@@ -1070,7 +1070,7 @@ rb_str_format(int argc, const VALUE *argv, VALUE fmt)
 		}
 		val = rb_int2str(num, 10);
 		len = RSTRING_LEN(val) + zero;
-		if (prec >= len) ++len; /* integer part 0 */
+		if (prec >= len) len = prec + 1; /* integer part 0 */
 		if (sign || (flags&FSPACE)) ++len;
 		if (prec > 0) ++len; /* period */
 		CHECK(len > width ? len : width);