diff --git a/src/libANGLE/Framebuffer.cpp b/src/libANGLE/Framebuffer.cpp
index 0672c1298a..bandaid 100644
--- a/src/libANGLE/Framebuffer.cpp
+++ b/src/libANGLE/Framebuffer.cpp
@@ -1690,15 +1690,14 @@ bool Framebuffer::partialClearNeedsInit(const Context *context,
     {
         ASSERT(HasSupportedStencilBitCount(glState.getDrawFramebuffer()));

-        // The least significant |stencilBits| of stencil mask state specify a
-        // mask. Compare the masks for differences only in those bits, ignoring any
-        // difference in the high bits.
-        const auto &depthStencil       = glState.getDepthStencilState();
-        const GLuint differentFwdMasks = depthStencil.stencilMask ^ depthStencil.stencilWritemask;
-        const GLuint differentBackMasks =
-            depthStencil.stencilBackMask ^ depthStencil.stencilBackWritemask;
-
-        if (((differentFwdMasks | differentBackMasks) & 0xFF) != 0)
+        // glClear honors GL_STENCIL_WRITEMASK only; GL_STENCIL_VALUE_MASK is
+        // irrelevant. The clear is a *full* clear of the stencil plane only when
+        // the writemask covers all stencil bits. If any bit is unwritable the
+        // clear is partial and the existing (uninitialized) bits would survive,
+        // so robust-resource-init must run first.
+        const auto &depthStencil = glState.getDepthStencilState();
+        if ((depthStencil.stencilWritemask & 0xFF) != 0xFF ||
+            (depthStencil.stencilBackWritemask & 0xFF) != 0xFF)
         {
             return true;
         }