--- a/layout/svg/nsSVGMaskFrameNEON.cpp
+++ b/layout/svg/nsSVGMaskFrameNEON.cpp
@@ -26,29 +26,29 @@ ComputesRGBLuminanceMask_NEON(const uint
   sourcePixel = aSourceData;
   int32_t remainderWidth = aSize.width % 8;
   int32_t roundedWidth = aSize.width - remainderWidth;
   uint16x8_t temp;
   uint8x8_t gray;
   uint8x8_t redVector = vdup_n_u8(redFactor);
   uint8x8_t greenVector = vdup_n_u8(greenFactor);
   uint8x8_t blueVector = vdup_n_u8(blueFactor);
-  uint8x8_t zeroVector = vdup_n_u8(0);
+  uint8x8_t fullBitVector = vdup_n_u8(255);
   uint8x8_t oneVector = vdup_n_u8(1);
   for (int32_t y = 0; y < aSize.height; y++) {
     // Calculate luminance by neon with 8 pixels per loop
     for (int32_t x = 0; x < roundedWidth; x += 8) {
       uint8x8x4_t argb  = vld4_u8(sourcePixel);
       temp = vmull_u8(argb.val[GFX_ARGB32_OFFSET_R], redVector); // temp = red * redFactor
       temp = vmlal_u8(temp, argb.val[GFX_ARGB32_OFFSET_G], greenVector); // temp += green * greenFactor
       temp = vmlal_u8(temp, argb.val[GFX_ARGB32_OFFSET_B], blueVector); // temp += blue * blueFactor
       gray = vshrn_n_u16(temp, 8); // gray = temp >> 8
 
       // Check alpha value
-      uint8x8_t alphaVector = vcgt_u8(argb.val[GFX_ARGB32_OFFSET_A], zeroVector);
+      uint8x8_t alphaVector = vtst_u8(argb.val[GFX_ARGB32_OFFSET_A], fullBitVector);
       gray = vmul_u8(gray, vand_u8(alphaVector, oneVector));
 
       // Put the result to the 8 pixels
       vst1_u8(destPixel, gray);
       sourcePixel += 8 * 4;
       destPixel += 8;
     }