diff --git a/src/element.ts b/src/element.ts
index c8150f6..1ea98ba 100644
--- a/src/element.ts
+++ b/src/element.ts
@@ -22,7 +22,8 @@ export function noShadowDOM() {
 
 export function createElementType<T>(
   BaseElement: typeof HTMLElement,
-  propDefinition: PropsDefinition<T>
+  propDefinition: PropsDefinition<T>,
+  { nestedCustomElements = window.customElements }: { nestedCustomElements?: CustomElementRegistry; }
 ) {
   const propKeys = Object.keys(propDefinition) as Array<
     keyof PropsDefinition<T>
@@ -59,7 +60,7 @@ export function createElementType<T>(
       const props = propValues<T>(this.props as PropsDefinition<T>),
         ComponentType = this.Component as
           | Function
-          | { new (...args: any[]): any },
+          | { new(...args: any[]): any },
         outerElement = currentElement;
       try {
         currentElement = this;
@@ -108,7 +109,13 @@ export function createElementType<T>(
     }
 
     get renderRoot() {
-      return this.shadowRoot || this.attachShadow({ mode: "open" });
+      return this.shadowRoot || (() => {
+        try {
+          return this.attachShadow({ mode: 'open', registry: nestedCustomElements } as any)
+        } catch (err) {
+          return this.attachShadow({ mode: 'open' })
+        }
+      })();
     }
 
     addReleaseCallback(fn: () => void) {
diff --git a/src/index.ts b/src/index.ts
index 50d34a1..9cc39f9 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -20,6 +20,7 @@ export type RegisterOptions = {
   BaseElement?: typeof HTMLElement;
   extension?: { extends: string };
   customElements?: CustomElementRegistry;
+  nestedCustomElements?: CustomElementRegistry;
 };
 export type PropDefinition<T> = uPropDefinition<T>;
 
@@ -31,7 +32,8 @@ export function register<T>(
   const {
     BaseElement = HTMLElement,
     extension,
-    customElements = window.customElements
+    customElements = window.customElements,
+    nestedCustomElements = customElements,
   } = options;
   return (ComponentType: ComponentType<T>) => {
     if (!tag) throw new Error("tag is required to register a Component");
@@ -42,7 +44,7 @@ export function register<T>(
       return ElementType;
     }
 
-    ElementType = createElementType(BaseElement, normalizePropDefs(props));
+    ElementType = createElementType(BaseElement, normalizePropDefs(props),{nestedCustomElements});
     ElementType.prototype.Component = ComponentType;
     ElementType.prototype.registeredTag = tag;
     customElements.define(tag, ElementType, extension);