diff --git a/src/gpu/GrGpuGLShaders.cpp b/src/gpu/GrGpuGLShaders.cpp
index 5ae6d65..bae699d 100644
--- a/src/gpu/GrGpuGLShaders.cpp
+++ b/src/gpu/GrGpuGLShaders.cpp
@@ -1028,7 +1028,7 @@
                 }
             }
             if (GrPixelConfigIsUnpremultiplied(texture->config())) {
-                stage.fInConfigFlags = StageDesc::kMulRGBByAlpha_InConfigFlag;
+                stage.fInConfigFlags |= StageDesc::kMulRGBByAlpha_InConfigFlag;
             }
 
             if (sampler.getFilter() == GrSamplerState::kConvolution_Filter) {