diff --git a/src/libANGLE/validationES.cpp b/src/libANGLE/validationES.cpp
index eb06b24a80..472f968e2f 100644
--- a/src/libANGLE/validationES.cpp
+++ b/src/libANGLE/validationES.cpp
@@ -4177,23 +4177,38 @@ const char *ValidateDrawStates(const Context *context, GLenum *outErrorCode)
     const BlendStateExt &blendStateExt = state.getBlendStateExt();
     if (ANGLE_UNLIKELY(blendStateExt.getUsesAdvancedBlendEquationMask().any()))
     {
-        const size_t drawBufferCount            = framebuffer->getDrawbufferStateCount();
-        uint32_t advancedBlendRenderTargetCount = 0;
-
-        for (size_t drawBufferIndex : blendStateExt.getUsesAdvancedBlendEquationMask())
+        // Per GLES 3.2 / KHR_blend_equation_advanced: when an advanced blend
+        // equation is in use on *any* enabled draw buffer, every color output
+        // other than zero must have its draw buffer set to GL_NONE.  This is
+        // also required to satisfy Vulkan
+        // VUID-VkPipelineColorBlendAttachmentState-advancedBlendIndependentBlend-01407/01408
+        // and -colorBlendOp-01410 on devices where the backend uses native
+        // VK_EXT_blend_operation_advanced.
+        const DrawBufferMask advancedMask = blendStateExt.getUsesAdvancedBlendEquationMask();
+        const DrawBufferMask enabledMask  = blendStateExt.getEnabledMask();
+        const size_t drawBufferCount      = framebuffer->getDrawbufferStateCount();
+
+        bool advancedBlendActive = false;
+        for (size_t drawBufferIndex : advancedMask)
         {
             if (drawBufferIndex < drawBufferCount &&
                 framebuffer->getDrawBufferState(drawBufferIndex) != GL_NONE &&
-                blendStateExt.getEnabledMask().test(drawBufferIndex) &&
-                blendStateExt.getUsesAdvancedBlendEquationMask().test(drawBufferIndex))
+                enabledMask.test(drawBufferIndex))
             {
-                ++advancedBlendRenderTargetCount;
+                advancedBlendActive = true;
+                break;
             }
         }
 
-        if (advancedBlendRenderTargetCount > 1)
+        if (advancedBlendActive)
         {
-            return kAdvancedBlendEquationWithMRT;
+            for (size_t drawBufferIndex = 1; drawBufferIndex < drawBufferCount; ++drawBufferIndex)
+            {
+                if (framebuffer->getDrawBufferState(drawBufferIndex) != GL_NONE)
+                {
+                    return kAdvancedBlendEquationWithMRT;
+                }
+            }
         }
     }