diff --git a/src/gpu/ccpr/GrCCCubicShader.cpp b/src/gpu/ccpr/GrCCCubicShader.cpp
index edff5ff..d0228d5 100644
--- a/src/gpu/ccpr/GrCCCubicShader.cpp
+++ b/src/gpu/ccpr/GrCCCubicShader.cpp
@@ -105,8 +105,9 @@
                                          const char* outputCoverage) const {
     f->codeAppendf("float k = %s.x, l = %s.y, m = %s.z;", fKLMD.fsIn(), fKLMD.fsIn(), fKLMD.fsIn());
     f->codeAppend ("float f = k*k*k - l*m;");
-    f->codeAppendf("float2 grad_f = %s * float2(k, 1);", fGradMatrix.fsIn());
-    f->codeAppendf("%s = clamp(0.5 - f * inversesqrt(dot(grad_f, grad_f)), 0, 1);", outputCoverage);
+    f->codeAppendf("float2 grad = %s * float2(k, 1);", fGradMatrix.fsIn());
+    f->codeAppend ("float fwidth = abs(grad.x) + abs(grad.y);");
+    f->codeAppendf("%s = clamp(0.5 - f/fwidth, 0, 1);", outputCoverage);
 
     f->codeAppendf("half d = min(%s.w, 0);", fKLMD.fsIn()); // Flat edge opposite the curve.
     // Wind is the sign of both L and/or M. Take the sign of whichever has the larger magnitude.
diff --git a/src/gpu/ccpr/GrCCQuadraticShader.cpp b/src/gpu/ccpr/GrCCQuadraticShader.cpp
index 287e63e..236c407 100644
--- a/src/gpu/ccpr/GrCCQuadraticShader.cpp
+++ b/src/gpu/ccpr/GrCCQuadraticShader.cpp
@@ -73,7 +73,8 @@
     f->codeAppendf("float x = %s.x, y = %s.y;", fCoord.fsIn(), fCoord.fsIn());
     f->codeAppend ("float f = x*x - y;");
     f->codeAppendf("float2 grad = %s.zw;", fCoord.fsIn());
-    f->codeAppendf("%s = clamp(0.5 - f * inversesqrt(dot(grad, grad)), 0, 1);", outputCoverage);
+    f->codeAppend ("float fwidth = abs(grad.x) + abs(grad.y);");
+    f->codeAppendf("%s = clamp(0.5 - f/fwidth, 0, 1);", outputCoverage);
 
     f->codeAppendf("half d = min(%s.x, 0);", fCoverages.fsIn()); // Flat edge opposite the curve.
     f->codeAppendf("half wind = %s.y;", fCoverages.fsIn());