diff --git a/libavcodec/msvideo1enc.c b/libavcodec/msvideo1enc.c
index b27eadf06b..6852c9868c 100644
--- a/libavcodec/msvideo1enc.c
+++ b/libavcodec/msvideo1enc.c
@@ -58,7 +58,7 @@ enum MSV1Mode{
 
 #define SKIP_PREFIX 0x8400
 #define SKIPS_MAX 0x03FF
-#define MKRGB555(in, off) ((in[off] << 10) | (in[off + 1] << 5) | (in[off + 2]))
+#define MKRGB555(in, off) (((in)[off] << 10) | ((in)[(off) + 1] << 5) | ((in)[(off) + 2]))
 
 static const int remap[16] = { 0, 1, 4, 5, 2, 3, 6, 7, 8, 9, 12, 13, 10, 11, 14, 15 };