diff --git a/libavcodec/libx264.c b/libavcodec/libx264.c
index 72a07169af..d81721c5f7 100644
--- a/libavcodec/libx264.c
+++ b/libavcodec/libx264.c
@@ -307,8 +307,10 @@ static av_cold int X264_close(AVCodecContext *avctx)
     av_freep(&avctx->extradata);
     av_freep(&x4->sei);
 
-    if (x4->enc)
+    if (x4->enc) {
         x264_encoder_close(x4->enc);
+        x4->enc = NULL;
+    }
 
     av_frame_free(&avctx->coded_frame);
 
@@ -889,6 +891,8 @@ AVCodec ff_libx264_encoder = {
     .priv_class       = &x264_class,
     .defaults         = x264_defaults,
     .init_static_data = X264_init_static,
+    .caps_internal    = FF_CODEC_CAP_INIT_THREADSAFE |
+                        FF_CODEC_CAP_INIT_CLEANUP,
 };
 
 AVCodec ff_libx264rgb_encoder = {