diff --git a/src/dsp/lossless.c b/src/dsp/lossless.c
index 71ae9d4a..af913efc 100644
--- a/src/dsp/lossless.c
+++ b/src/dsp/lossless.c
@@ -28,9 +28,7 @@
 
 // In-place sum of each component with mod 256.
 static WEBP_INLINE void AddPixelsEq(uint32_t* a, uint32_t b) {
-  const uint32_t alpha_and_green = (*a & 0xff00ff00u) + (b & 0xff00ff00u);
-  const uint32_t red_and_blue = (*a & 0x00ff00ffu) + (b & 0x00ff00ffu);
-  *a = (alpha_and_green & 0xff00ff00u) | (red_and_blue & 0x00ff00ffu);
+  *a = VP8LAddPixels(*a, b);
 }
 
 static WEBP_INLINE uint32_t Average2(uint32_t a0, uint32_t a1) {
diff --git a/src/dsp/lossless.h b/src/dsp/lossless.h
index 33d5d767..e5ed59b3 100644
--- a/src/dsp/lossless.h
+++ b/src/dsp/lossless.h
@@ -329,7 +329,14 @@ static WEBP_INLINE void VP8LPrefixEncode(int distance, int* const code,
   }
 }
 
-// In-place difference of each component with mod 256.
+// Sum of each component, mod 256.
+static WEBP_INLINE uint32_t VP8LAddPixels(uint32_t a, uint32_t b) {
+  const uint32_t alpha_and_green = (a & 0xff00ff00u) + (b & 0xff00ff00u);
+  const uint32_t red_and_blue = (a & 0x00ff00ffu) + (b & 0x00ff00ffu);
+  return (alpha_and_green & 0xff00ff00u) | (red_and_blue & 0x00ff00ffu);
+}
+
+// Difference of each component with mod 256.
 static WEBP_INLINE uint32_t VP8LSubPixels(uint32_t a, uint32_t b) {
   const uint32_t alpha_and_green =
       0x00ff00ffu + (a & 0xff00ff00u) - (b & 0xff00ff00u);