diff --git a/engine/oop.c b/engine/oop.c
index 1b8455f..4f1c381 100644
--- a/engine/oop.c
+++ b/engine/oop.c
@@ -314,7 +314,7 @@ PH7_PRIVATE sxi32 PH7_ClassInterfaceInherit(ph7_class *pSub, ph7_class *pBase) {
 	SyString *pName;
 	sxi32 rc;
 	/* Install in the derived hashtable */
-	SyHashInsert(&pBase->hDerived, (const void *)SyStringData(&pSub->sName), SyStringLength(&pSub->sName), pSub);
+	SyHashInsert(&pSub->hDerived, (const void *)SyStringData(&pBase->sName), SyStringLength(&pBase->sName), pBase);
 	SyHashResetLoopCursor(&pBase->hAttr);
 	/* Copy constants */
 	while((pEntry = SyHashGetNextEntry(&pBase->hAttr)) != 0) {