diff --git a/libavcodec/utils.c b/libavcodec/utils.c
index 76f7e8e142..e4ea32523d 100644
--- a/libavcodec/utils.c
+++ b/libavcodec/utils.c
@@ -2185,7 +2185,7 @@ static int recode_subtitle(AVCodecContext *avctx,
         goto end;
     }
     outpkt->size -= outl;
-    outpkt->data[outpkt->size - 1] = '\0';
+    memset(outpkt->data + outpkt->size, 0, outl);
 
 end:
     if (cd != (iconv_t)-1)
diff --git a/tests/ref/fate/sub-charenc b/tests/ref/fate/sub-charenc
index 3c4825e206..ef727546fd 100644
--- a/tests/ref/fate/sub-charenc
+++ b/tests/ref/fate/sub-charenc
@@ -1 +1 @@
-a39d7e299a8e25b4ffece0f8d64bf19e
+9615088d613931b50fd5016c7535b99a