diff --git a/src/core/gpu.cpp b/src/core/gpu.cpp
index db807a997..28529a0a3 100644
--- a/src/core/gpu.cpp
+++ b/src/core/gpu.cpp
@@ -870,7 +870,7 @@ void GPU::UpdateVRAM(u32 x, u32 y, u32 width, u32 height, const void* data)
       {
         // TODO: Handle unaligned reads...
         u16* pixel_ptr = &dst_row_ptr[(x + col++) % VRAM_WIDTH];
-        if (((*pixel_ptr) & mask_and) == mask_and)
+        if (((*pixel_ptr) & mask_and) == 0)
           *pixel_ptr = *(src_ptr++) | mask_or;
       }
     }
@@ -892,7 +892,7 @@ void GPU::CopyVRAM(u32 src_x, u32 src_y, u32 dst_x, u32 dst_y, u32 width, u32 he
     {
       const u16 src_pixel = src_row_ptr[(src_x + col) % VRAM_WIDTH];
       u16* dst_pixel_ptr = &dst_row_ptr[(dst_x + col) % VRAM_WIDTH];
-      if ((*dst_pixel_ptr & mask_and) == mask_and)
+      if ((*dst_pixel_ptr & mask_and) == 0)
         *dst_pixel_ptr = src_pixel | mask_or;
     }
   }
diff --git a/src/core/gpu.h b/src/core/gpu.h
index 70bf8e1c7..0d97806c9 100644
--- a/src/core/gpu.h
+++ b/src/core/gpu.h
@@ -390,9 +390,17 @@ protected:
       return ((bits & MASK) == MASK);
     }
 
-    // During transfer/render operations, if ((dst_pixel & mask_and) == mask_and) { pixel = src_pixel | mask_or }
-    u16 GetMaskAND() const { return check_mask_before_draw ? 0x8000 : 0x0000; }
-    u16 GetMaskOR() const { return set_mask_while_drawing ? 0x8000 : 0x0000; }
+    // During transfer/render operations, if ((dst_pixel & mask_and) == 0) { pixel = src_pixel | mask_or }
+    u16 GetMaskAND() const
+    {
+      // return check_mask_before_draw ? 0x8000 : 0x0000;
+      return Truncate16((bits << 3) & 0x8000);
+    }
+    u16 GetMaskOR() const
+    {
+      // return set_mask_while_drawing ? 0x8000 : 0x0000;
+      return Truncate16((bits << 4) & 0x8000);
+    }
   } m_GPUSTAT = {};
 
   struct DrawMode
diff --git a/src/core/gpu_sw.cpp b/src/core/gpu_sw.cpp
index 648501af3..31d33ea4c 100644
--- a/src/core/gpu_sw.cpp
+++ b/src/core/gpu_sw.cpp
@@ -570,7 +570,7 @@ void GPU_SW::ShadePixel(u32 x, u32 y, u8 color_r, u8 color_g, u8 color_b, u8 tex
   }
 
   const u16 mask_and = m_GPUSTAT.GetMaskAND();
-  if ((bg_color.bits & mask_and) != mask_and)
+  if ((bg_color.bits & mask_and) != 0)
     return;
 
   SetPixel(static_cast<u32>(x), static_cast<u32>(y), color.bits | m_GPUSTAT.GetMaskOR());