diff --git a/src/libImaging/ImagingUtils.h b/src/libImaging/ImagingUtils.h
index 0c0c1eda9..d8e4689ad 100644
--- a/src/libImaging/ImagingUtils.h
+++ b/src/libImaging/ImagingUtils.h
@@ -14,16 +14,16 @@
 #define MASK_UINT32_CHANNEL_3 0xff000000
 #endif
 
-#define SHIFTFORDIV255(a) ((((a) >> 8) + a) >> 8)
+#define SHIFTFORDIV255(a) ((((a) >> 8) + (a)) >> 8)
 
 /* like (a * b + 127) / 255), but much faster on most platforms */
 #define MULDIV255(a, b, tmp) (tmp = (a) * (b) + 128, SHIFTFORDIV255(tmp))
 
 #define DIV255(a, tmp) (tmp = (a) + 128, SHIFTFORDIV255(tmp))
 
-#define BLEND(mask, in1, in2, tmp1) DIV255(in1 *(255 - mask) + in2 * mask, tmp1)
+#define BLEND(mask, in1, in2, tmp1) DIV255((in1) * (255 - (mask)) + (in2) * (mask), tmp1)
 
-#define PREBLEND(mask, in1, in2, tmp1) (MULDIV255(in1, (255 - mask), tmp1) + in2)
+#define PREBLEND(mask, in1, in2, tmp1) (MULDIV255(in1, 255 - (mask), tmp1) + (in2))
 
 #define CLIP8(v) ((v) <= 0 ? 0 : (v) < 256 ? (v) : 255)