diff --git a/gm/perlinnoise.cpp b/gm/perlinnoise.cpp
index d61e25e023..5f30772151 100644
--- a/gm/perlinnoise.cpp
+++ b/gm/perlinnoise.cpp
@@ -25,7 +25,6 @@ namespace {
 enum class Type {
     kFractalNoise,
     kTurbulence,
-    kImproved,
 };
 
 class PerlinNoiseGM : public skiagm::GM {
@@ -35,7 +34,7 @@ class PerlinNoiseGM : public skiagm::GM {
 
     SkString onShortName() override { return SkString("perlinnoise"); }
 
-    SkISize onISize() override { return {200, 600}; }
+    SkISize onISize() override { return {200, 500}; }
 
     void drawRect(SkCanvas* canvas, int x, int y, const SkPaint& paint, const SkISize& size) {
         canvas->save();
@@ -47,33 +46,14 @@ class PerlinNoiseGM : public skiagm::GM {
     }
 
     void test(SkCanvas* canvas, int x, int y, Type type,
-              float baseFrequencyX, float baseFrequencyY, int numOctaves, float seedOrZ,
+              float baseFrequencyX, float baseFrequencyY, int numOctaves, float seed,
               bool stitchTiles) {
         SkISize tileSize = SkISize::Make(fSize.width() / 2, fSize.height() / 2);
-        sk_sp<SkShader> shader;
-        switch (type) {
-            case Type::kFractalNoise:
-                shader = SkPerlinNoiseShader::MakeFractalNoise(baseFrequencyX,
-                                                               baseFrequencyY,
-                                                               numOctaves,
-                                                               seedOrZ,
-                                                               stitchTiles ? &tileSize : nullptr);
-                break;
-            case Type::kTurbulence:
-                shader = SkPerlinNoiseShader::MakeTurbulence(baseFrequencyX,
-                                                             baseFrequencyY,
-                                                             numOctaves,
-                                                             seedOrZ,
-                                                             stitchTiles ? &tileSize : nullptr);
-                break;
-            case Type::kImproved:
-                SkASSERT(!stitchTiles);
-                shader = SkPerlinNoiseShader::MakeImprovedNoise(baseFrequencyX,
-                                                                baseFrequencyY,
-                                                                numOctaves,
-                                                                seedOrZ);
-                break;
-        }
+        sk_sp<SkShader> shader = (type == Type::kFractalNoise) ?
+            SkPerlinNoiseShader::MakeFractalNoise(baseFrequencyX, baseFrequencyY, numOctaves,
+                                                  seed, stitchTiles ? &tileSize : nullptr) :
+            SkPerlinNoiseShader::MakeTurbulence(baseFrequencyX, baseFrequencyY, numOctaves,
+                                                seed, stitchTiles ? &tileSize : nullptr);
         SkPaint paint;
         paint.setShader(std::move(shader));
         if (stitchTiles) {
@@ -111,16 +91,11 @@ class PerlinNoiseGM : public skiagm::GM {
         test(canvas, 100, 300, Type::kFractalNoise,
              0.1f, 0.1f, 3, 4, false);
 
-        test(canvas,   0, 400, Type::kImproved,
-             0.0125f, 0.0125f, 4, 0, false);
-        test(canvas, 100, 400, Type::kImproved,
-             0.125f, 0.0075f, 2, 0, false);
-
         canvas->scale(0.75f, 1.0f);
 
-        test(canvas,   0, 500, Type::kFractalNoise,
+        test(canvas,   0, 400, Type::kFractalNoise,
              0.1f, 0.1f, 2, 0, false);
-        test(canvas, 100, 500, Type::kFractalNoise,
+        test(canvas, 100, 400, Type::kFractalNoise,
              0.1f, 0.05f, 1, 0, true);
     }
 
diff --git a/src/shaders/SkPerlinNoiseShader.cpp b/src/shaders/SkPerlinNoiseShader.cpp
index f429d0bd57..1dc538c4f3 100644
--- a/src/shaders/SkPerlinNoiseShader.cpp
+++ b/src/shaders/SkPerlinNoiseShader.cpp
@@ -1222,7 +1222,7 @@ void GrGLImprovedPerlinNoise::emitCode(EmitArgs& args) {
     };
     SkString samplePerm = this->invokeChild(0, "half4(1)", args, "float2(x, 0.5)");
     SkString permFuncName = fragBuilder->getMangledFunctionName("perm");
-    SkString permCode = SkStringPrintf("return %s.a * 255;", samplePerm.c_str());
+    SkString permCode = SkStringPrintf("return %s.r * 255;", samplePerm.c_str());
     fragBuilder->emitFunction(kHalf_GrSLType, permFuncName.c_str(),
                               {permArgs, SK_ARRAY_COUNT(permArgs)}, permCode.c_str());