diff --git a/libavformat/avienc.c b/libavformat/avienc.c
index c9d8b7fbe4..e05e02281d 100644
--- a/libavformat/avienc.c
+++ b/libavformat/avienc.c
@@ -70,7 +70,7 @@ typedef struct  {
     AVIIndex indexes;
 } AVIStream;
 
-static inline AVIIentry *avi_get_ientry(AVIIndex *idx, int ent_id)
+static inline AVIIentry *avi_get_ientry(const AVIIndex *idx, int ent_id)
 {
     int cl = ent_id / AVI_INDEX_CLUSTER_SIZE;
     int id = ent_id % AVI_INDEX_CLUSTER_SIZE;