diff --git a/src/index.tsx b/src/index.tsx
index a14ef6b..e47c885 100644
--- a/src/index.tsx
+++ b/src/index.tsx
@@ -147,8 +147,10 @@ function makeStyle(def: TagDef) {
   return style
 }
 
+const ROOT_PROPS_KEY = '_forgeRootProps'
+
 // turns a TagDef into a JSX component
-function makeComponent(baseName: string, rootDef: TagDef, rootProps: Record<string, any>, partName?: string) {
+function makeComponent(baseName: string, rootDef: TagDef, partName?: string) {
   const def = partName ? rootDef.parts?.[partName]! : rootDef
   const base = def.base ?? 'div'
 
@@ -167,7 +169,7 @@ function makeComponent(baseName: string, rootDef: TagDef, rootProps: Record<stri
     }
   }
 
-  return ({ children, ...props }: { children: any, [key: string]: any }) => {
+  return ({ [ROOT_PROPS_KEY]: rootProps = {}, children, ...props }: { [ROOT_PROPS_KEY]?: Record<string, any>, children: any, [key: string]: any }) => {
     const classNames = [makeClassName(baseName, partName)]
 
     const allProps = { ...rootProps, ...props }
@@ -286,14 +288,28 @@ export function define(nameOrDef: string | TagDef, defIfNamed?: TagDef) {
   if (styles[name]) throw `${name} is already defined! Must use unique names.`
   registerStyles(name, def)
 
+  // ensure component function identity doesn't change between renders
+  const components: Record<string, (props: any) => any> = {}
+
+  for (const [partName] of Object.entries(def.parts ?? {}))
+    components[partName] = makeComponent(name, def, partName)
+
+  const RootComponent = makeComponent(name, def)
+
   return (props: Record<string, any>) => {
-    const parts: Record<string, Function> = {}
+    if (def.render) {
+      // For custom render, create parts object that injects _forgeRootProps
+      const parts: Record<string, (partProps: any) => any> = {}
 
-    for (const [part] of Object.entries(def.parts ?? {}))
-      parts[part] = makeComponent(name, def, props, part)
+      for (const [partName, Comp] of Object.entries(components))
+        parts[partName] = (partProps: any) => <Comp {...{ [ROOT_PROPS_KEY]: props }} {...partProps} />
 
-    parts.Root = makeComponent(name, def, props)
-    return def.render?.({ props, parts }) ?? <parts.Root {...props}>{props.children}</parts.Root>
+      parts.Root = (partProps: any) => <RootComponent {...{ [ROOT_PROPS_KEY]: props }} {...partProps} />
+      return def.render({ props, parts })
+    }
+
+    // Default render
+    return <RootComponent {...{ [ROOT_PROPS_KEY]: props }} {...props}>{props.children}</RootComponent>
   }
 }