diff --git a/libavcodec/wmalosslessdec.c b/libavcodec/wmalosslessdec.c
index 8885487980..c6c13fb417 100644
--- a/libavcodec/wmalosslessdec.c
+++ b/libavcodec/wmalosslessdec.c
@@ -164,7 +164,7 @@ typedef struct WmallDecodeCtx {
     int transient_pos[WMALL_MAX_CHANNELS];
     int seekable_tile;
 
-    int ave_sum[WMALL_MAX_CHANNELS];
+    unsigned ave_sum[WMALL_MAX_CHANNELS];
 
     int channel_residues[WMALL_MAX_CHANNELS][WMALL_BLOCK_MAX_SIZE];