diff --git a/src/V3AstNodes.cpp b/src/V3AstNodes.cpp
index 241d91078..076d94669 100644
--- a/src/V3AstNodes.cpp
+++ b/src/V3AstNodes.cpp
@@ -1171,6 +1171,12 @@ void AstClass::repairCache() {
     clearCache();
     for (AstNode* itemp = membersp(); itemp; itemp = itemp->nextp()) { insertCache(itemp); }
 }
+bool AstClass::isClassExtendedFrom(const AstClass* refClassp, const AstClass* baseClassp) {
+    // TAIL RECURSIVE
+    if (!refClassp || !baseClassp) return false;
+    if (refClassp == baseClassp) return true;
+    return isClassExtendedFrom(refClassp->extendsp()->classp(), baseClassp);
+}
 void AstClass::dump(std::ostream& str) const {
     this->AstNode::dump(str);
     if (isExtended()) str << " [EXT]";
diff --git a/src/V3AstNodes.h b/src/V3AstNodes.h
index 38fa9d26d..63f91c1a5 100644
--- a/src/V3AstNodes.h
+++ b/src/V3AstNodes.h
@@ -341,6 +341,9 @@ public:
     void isExtended(bool flag) { m_extended = flag; }
     bool isVirtual() const { return m_virtual; }
     void isVirtual(bool flag) { m_virtual = flag; }
+    // Return true if this class is an extension of base class (SLOW)
+    // Accepts nullptrs
+    static bool isClassExtendedFrom(const AstClass* refClassp, const AstClass* baseClassp);
 };
 
 class AstClassExtends final : public AstNode {
diff --git a/src/V3WidthCommit.h b/src/V3WidthCommit.h
index 52344c197..b84b5a110 100644
--- a/src/V3WidthCommit.h
+++ b/src/V3WidthCommit.h
@@ -133,7 +133,7 @@ private:
             const char* how = nullptr;
             if (local && defClassp && refClassp != defClassp) {
                 how = "'local'";
-            } else if (prot && defClassp && !classExtendedRecurse(refClassp, defClassp)) {
+            } else if (prot && defClassp && !AstClass::isClassExtendedFrom(refClassp, defClassp)) {
                 how = "'protected'";
             }
             if (how) {
@@ -149,12 +149,6 @@ private:
             }
         }
     }
-    static bool classExtendedRecurse(const AstClass* refClassp, const AstClass* defClassp) {
-        // Return true if refClassp is an extends class of defClassp
-        if (!refClassp || !defClassp) return false;
-        if (refClassp == defClassp) return true;
-        return classExtendedRecurse(refClassp->extendsp()->classp(), defClassp);
-    }
 
     // VISITORS
     virtual void visit(AstNodeModule* nodep) override {