diff --git a/layout/style/nsRuleNode.cpp b/layout/style/nsRuleNode.cpp
index 206eb275bdf7..9d4c766b27d2 100644
--- a/layout/style/nsRuleNode.cpp
+++ b/layout/style/nsRuleNode.cpp
@@ -5945,6 +5945,7 @@ nsRuleNode::ComputeDisplayData(void* aStartStruct,
           nsCSSProps::LookupProperty(buffer,
                                      nsCSSProps::eEnabledForAllContent);
         if (prop != eCSSProperty_UNKNOWN &&
+            prop != eCSSPropertyExtra_variable &&
             nsCSSProps::PropHasFlags(prop,
                                      CSS_PROPERTY_CREATES_STACKING_CONTEXT))
         {