diff --git a/libavcodec/a64multienc.c b/libavcodec/a64multienc.c
index 5f4825d55d..55616c8524 100644
--- a/libavcodec/a64multienc.c
+++ b/libavcodec/a64multienc.c
@@ -407,7 +407,7 @@ AVCodec ff_a64multi_encoder = {
     .close          = a64multi_close_encoder,
     .pix_fmts       = (const enum AVPixelFormat[]) {AV_PIX_FMT_GRAY8, AV_PIX_FMT_NONE},
     .capabilities   = AV_CODEC_CAP_DELAY,
-    .caps_internal  = FF_CODEC_CAP_INIT_CLEANUP,
+    .caps_internal  = FF_CODEC_CAP_INIT_CLEANUP | FF_CODEC_CAP_INIT_THREADSAFE,
 };
 #endif
 #if CONFIG_A64MULTI5_ENCODER
@@ -422,6 +422,6 @@ AVCodec ff_a64multi5_encoder = {
     .close          = a64multi_close_encoder,
     .pix_fmts       = (const enum AVPixelFormat[]) {AV_PIX_FMT_GRAY8, AV_PIX_FMT_NONE},
     .capabilities   = AV_CODEC_CAP_DELAY,
-    .caps_internal  = FF_CODEC_CAP_INIT_CLEANUP,
+    .caps_internal  = FF_CODEC_CAP_INIT_CLEANUP | FF_CODEC_CAP_INIT_THREADSAFE,
 };
 #endif