diff --git a/libavcodec/aacdec.c b/libavcodec/aacdec.c
index f180d78f5b..44869c5e7d 100644
--- a/libavcodec/aacdec.c
+++ b/libavcodec/aacdec.c
@@ -1242,7 +1242,7 @@ static void decode_mid_side_stereo(ChannelElement *cpe, GetBitContext *gb,
         for (idx = 0; idx < cpe->ch[0].ics.num_window_groups * cpe->ch[0].ics.max_sfb; idx++)
             cpe->ms_mask[idx] = get_bits1(gb);
     } else if (ms_present == 2) {
-        memset(cpe->ms_mask, 1, cpe->ch[0].ics.num_window_groups * cpe->ch[0].ics.max_sfb * sizeof(cpe->ms_mask[0]));
+        memset(cpe->ms_mask, 1,  sizeof(cpe->ms_mask[0]) * cpe->ch[0].ics.num_window_groups * cpe->ch[0].ics.max_sfb);
     }
 }