diff --git a/libavcodec/gsmdec.c b/libavcodec/gsmdec.c
index 373ed087ef..c169112311 100644
--- a/libavcodec/gsmdec.c
+++ b/libavcodec/gsmdec.c
@@ -121,6 +121,7 @@ const AVCodec ff_gsm_decoder = {
     .decode         = gsm_decode_frame,
     .flush          = gsm_flush,
     .capabilities   = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_CHANNEL_CONF,
+    .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE,
 };
 #endif
 #if CONFIG_GSM_MS_DECODER
@@ -134,5 +135,6 @@ const AVCodec ff_gsm_ms_decoder = {
     .decode         = gsm_decode_frame,
     .flush          = gsm_flush,
     .capabilities   = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_CHANNEL_CONF,
+    .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE,
 };
 #endif