--- a/dom/canvas/WebGLContextValidate.cpp
+++ b/dom/canvas/WebGLContextValidate.cpp
@@ -449,16 +449,17 @@ WebGLContext::InitAndValidateGL(FailureR
     AssertUintParamCorrect(gl, LOCAL_GL_STENCIL_BACK_VALUE_MASK, mStencilValueMaskBack);
     AssertUintParamCorrect(gl, LOCAL_GL_STENCIL_WRITEMASK,       mStencilWriteMaskFront);
     AssertUintParamCorrect(gl, LOCAL_GL_STENCIL_BACK_WRITEMASK,  mStencilWriteMaskBack);
 
     mDitherEnabled = true;
     mRasterizerDiscardEnabled = false;
     mScissorTestEnabled = false;
     mDepthTestEnabled = 0;
+    mStencilTestEnabled = 0;
     mGenerateMipmapHint = LOCAL_GL_DONT_CARE;
 
     // Bindings, etc.
     mActiveTexture = 0;
     mDefaultFB_DrawBuffer0 = LOCAL_GL_BACK;
 
     mEmitContextLostErrorOnce = true;
     mWebGLError = LOCAL_GL_NO_ERROR;