diff --git a/src/transcode.c b/src/transcode.c
index 23ceb353..80bf619e 100644
--- a/src/transcode.c
+++ b/src/transcode.c
@@ -937,7 +937,7 @@ open_output(struct encode_ctx *ctx, struct decode_ctx *src_ctx)
     }
 
   // Clear AVFMT_NOFILE bit, it is not allowed as we will set our own AVIOContext
-  oformat->flags = ~AVFMT_NOFILE;
+  oformat->flags &= ~AVFMT_NOFILE;
 
   CHECK_NULL(L_XCODE, ctx->ofmt_ctx = avformat_alloc_context());