diff --git a/src/gpu/gl/debug/GrGLCreateDebugInterface.cpp b/src/gpu/gl/debug/GrGLCreateDebugInterface.cpp
index 685e18d085..5419bff8d4 100644
--- a/src/gpu/gl/debug/GrGLCreateDebugInterface.cpp
+++ b/src/gpu/gl/debug/GrGLCreateDebugInterface.cpp
@@ -163,6 +163,9 @@ GrGLvoid GR_GL_FUNCTION_TYPE debugGLReadPixels(GrGLint x, GrGLint y,
         case GR_GL_RGB:
             componentsPerPixel = 3;
             break;
+        case GR_GL_RED:
+            componentsPerPixel = 1;
+            break;
         default:
             GrAlwaysAssert(false);
             break;