diff --git a/libavformat/mov.c b/libavformat/mov.c
index b4ff1df2eb..ce61250eac 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -1842,7 +1842,7 @@ static void mov_build_index(MOVContext *mov, AVStream *st)
         unsigned int stts_sample = 0;
         unsigned int sample_size;
         unsigned int distance = 0;
-        int key_off = sc->keyframes && sc->keyframes[0] == 1;
+        int key_off = sc->keyframe_count && sc->keyframes[0] == 1;
 
         current_dts -= sc->dts_shift;