diff --git a/src/pixie/internal.nim b/src/pixie/internal.nim
index 9368923..ecd0544 100644
--- a/src/pixie/internal.nim
+++ b/src/pixie/internal.nim
@@ -95,25 +95,18 @@ when defined(amd64) and not defined(pixieNoSimd):
 
   proc unpackAlphaValues*(v: M128i): M128i {.inline.} =
     ## Unpack the first 32 bits into 4 rgba(0, 0, 0, value)
-    let
-      first32 = cast[M128i]([uint32.high, 0, 0, 0])                # First 32 bits
-      alphaMask = mm_set1_epi32(cast[int32](0xff000000))           # Only `a`
-
-    result = mm_shuffle_epi32(v, MM_SHUFFLE(0, 0, 0, 0))
+    let mask = cast[M128i]([uint8.high.uint64, 0])
 
     var
-      i = mm_and_si128(result, first32)
-      j = mm_and_si128(result, mm_slli_si128(first32, 4))
-      k = mm_and_si128(result, mm_slli_si128(first32, 8))
-      l = mm_and_si128(result, mm_slli_si128(first32, 12))
+      i = mm_and_si128(v, mask)
+      j = mm_and_si128(v, mm_slli_si128(mask, 1))
+      k = mm_and_si128(v, mm_slli_si128(mask, 2))
+      l = mm_and_si128(v, mm_slli_si128(mask, 3))
 
-    # Shift the values to `a`
+    # Shift the values to uint32 `a`
     i = mm_slli_si128(i, 3)
-    j = mm_slli_si128(j, 2)
-    k = mm_slli_si128(k, 1)
-    # l = mm_slli_si128(l, 0)
+    j = mm_slli_si128(j, 6)
+    k = mm_slli_si128(k, 9)
+    l = mm_slli_si128(l, 12)
 
-    result = mm_and_si128(
-      mm_or_si128(mm_or_si128(i, j), mm_or_si128(k, l)),
-      alphaMask
-    )
+    result = mm_or_si128(mm_or_si128(i, j), mm_or_si128(k, l))