diff --git a/libavformat/mov.c b/libavformat/mov.c
index f280f360b6..f01502a5f8 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -1005,6 +1005,7 @@ static int mov_read_adrm(MOVContext *c, AVIOContext *pb, MOVAtom atom)
     sha = av_sha_alloc();
     if (!sha)
         return AVERROR(ENOMEM);
+    av_free(c->aes_decrypt);
     c->aes_decrypt = av_aes_alloc();
     if (!c->aes_decrypt) {
         ret = AVERROR(ENOMEM);