diff --git a/libavcodec/lagarith.c b/libavcodec/lagarith.c
index 69899e423e..3b5e956f16 100644
--- a/libavcodec/lagarith.c
+++ b/libavcodec/lagarith.c
@@ -29,6 +29,7 @@
 
 #include "avcodec.h"
 #include "get_bits.h"
+#include "internal.h"
 #include "mathops.h"
 #include "lagarithrac.h"
 #include "lossless_videodsp.h"
@@ -721,4 +722,5 @@ const AVCodec ff_lagarith_decoder = {
     .init           = lag_decode_init,
     .decode         = lag_decode_frame,
     .capabilities   = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_FRAME_THREADS,
+    .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE,
 };