diff --git a/src/fmt_fp.c b/src/fmt_fp.c
index a1743a0de..3eed1177e 100644
--- a/src/fmt_fp.c
+++ b/src/fmt_fp.c
@@ -118,7 +118,9 @@ mrb_format_float(mrb_float f, char *buf, size_t buf_size, char fmt, int prec, ch
       *s++ = 'N' ^ uc;
       *s++ = 'A' ^ uc;
       *s++ = 'N' ^ uc;
-      goto ret;
+    ret:
+      *s = '\0';
+      return (int)(s - buf);
     }
   }
 
@@ -363,7 +365,7 @@ mrb_format_float(mrb_float f, char *buf, size_t buf_size, char fmt, int prec, ch
     *s++ = '0' + (e / 10);
     *s++ = '0' + (e % 10);
   }
- ret:
+
   *s = '\0';
   return (int)(s - buf);
 }