diff --git a/tests/SrcOverTest.cpp b/tests/SrcOverTest.cpp
new file mode 100644
index 0000000..cf429de
--- /dev/null
+++ b/tests/SrcOverTest.cpp
@@ -0,0 +1,71 @@
+#include "Test.h"
+#include "SkColorPriv.h"
+#include "SkXfermode.h"
+
+// our std SkAlpha255To256
+static int test_srcover0(unsigned dst, unsigned alpha) {
+    return alpha + SkAlphaMul(dst, SkAlpha255To256(255 - alpha));
+}
+
+// faster hack +1
+static int test_srcover1(unsigned dst, unsigned alpha) {
+    return alpha + SkAlphaMul(dst, 256 - alpha);
+}
+
+// slower "correct"
+static int test_srcover2(unsigned dst, unsigned alpha) {
+    return alpha + SkMulDiv255Round(dst, 255 - alpha);
+}
+
+static void test_srcover_hack(skiatest::Reporter* reporter) {
+    /*  Here's the idea. Can we ensure that when we blend on top of an opaque
+        dst, that the result always stay's opaque (i.e. exactly 255)?
+     */
+    
+    unsigned i;
+    int opaqueCounter0 = 0;
+    int opaqueCounter1 = 0;
+    int opaqueCounter2 = 0;
+    for (i = 0; i <= 255; i++) {
+        unsigned result0 = test_srcover0(0xFF, i);
+        unsigned result1 = test_srcover1(0xFF, i);
+        unsigned result2 = test_srcover2(0xFF, i);
+        opaqueCounter0 += (result0 == 0xFF);
+        opaqueCounter1 += (result1 == 0xFF);
+        opaqueCounter2 += (result2 == 0xFF);
+    }
+#if 0
+    SkDebugf("---- opaque test: [%d %d %d]\n",
+             opaqueCounter0, opaqueCounter1, opaqueCounter2);
+#endif
+    // we acknowledge that technique0 does not always return opaque
+    REPORTER_ASSERT(reporter, opaqueCounter0 == 129);
+    REPORTER_ASSERT(reporter, opaqueCounter1 == 256);
+    REPORTER_ASSERT(reporter, opaqueCounter2 == 256);
+    
+    // Now ensure that we never over/underflow a byte
+    for (i = 0; i <= 255; i++) {
+        for (unsigned dst = 0; dst <= 255; dst++) {
+            unsigned r0 = test_srcover0(dst, i);
+            unsigned r1 = test_srcover1(dst, i);
+            unsigned r2 = test_srcover2(dst, i);
+            unsigned max = SkMax32(dst, i);
+            // ignore the known failure
+            if (dst != 255) {
+                REPORTER_ASSERT(reporter, r0 <= 255 && r0 >= max);
+            }
+            REPORTER_ASSERT(reporter, r1 <= 255 && r1 >= max);
+            REPORTER_ASSERT(reporter, r2 <= 255 && r2 >= max);
+            
+#if 0
+            // this shows where r1 (faster) differs from r2 (more exact)
+            if (r1 != r2) {
+                SkDebugf("--- dst=%d i=%d r1=%d r2=%d exact=%g\n", dst, i, r1, r2, i + dst - dst*i/255.0f);
+            }
+#endif
+        }
+    }
+}
+
+#include "TestClassDef.h"
+DEFINE_TESTCLASS("SrcOver", SrcOverTestClass, test_srcover_hack)