diff --git a/Userland/Libraries/LibWeb/DOM/Element.h b/Userland/Libraries/LibWeb/DOM/Element.h
index e1eb9369e4..6ce4597c32 100644
--- a/Userland/Libraries/LibWeb/DOM/Element.h
+++ b/Userland/Libraries/LibWeb/DOM/Element.h
@@ -96,7 +96,7 @@ public:
     const ShadowRoot* shadow_root() const { return m_shadow_root; }
     void set_shadow_root(RefPtr<ShadowRoot>);
 
-    Optional<CSS::StyleResolver::CustomPropertyResolutionTuple> resolve_custom_property(const String& custom_property_name)
+    Optional<CSS::StyleResolver::CustomPropertyResolutionTuple> resolve_custom_property(const String& custom_property_name) const
     {
         return m_custom_properties.get(custom_property_name);
     }