diff --git a/tools/target_dec_fuzzer.c b/tools/target_dec_fuzzer.c
index dc7efe914d..f43f417088 100644
--- a/tools/target_dec_fuzzer.c
+++ b/tools/target_dec_fuzzer.c
@@ -206,7 +206,7 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
             if (flags & 8)
                 ctx->err_recognition |= AV_EF_EXPLODE;
         }
-        if (flags & 0x10)
+        if ((flags & 0x10) && c->id != AV_CODEC_ID_H264)
             ctx->flags2 |= AV_CODEC_FLAG2_FAST;
 
         if (flags & 0x40)