diff --git a/libavcodec/mv30.c b/libavcodec/mv30.c
index 9f28199478..59088d84f8 100644
--- a/libavcodec/mv30.c
+++ b/libavcodec/mv30.c
@@ -102,7 +102,7 @@ static void get_qtable(int16_t *table, int quant, const uint8_t *quant_tab)
     }
 }
 
-static inline void idct_1d(int *blk, int step)
+static inline void idct_1d(unsigned *blk, int step)
 {
     const unsigned t0 = blk[0 * step] + blk[4 * step];
     const unsigned t1 = blk[0 * step] - blk[4 * step];