diff --git a/dist/dialog-polyfill.esm.js b/dist/dialog-polyfill.esm.js
index da774bc..5aea677 100644
--- a/dist/dialog-polyfill.esm.js
+++ b/dist/dialog-polyfill.esm.js
@@ -64,7 +64,9 @@ function findNearestDialog(el) {
     if (el.localName === 'dialog') {
       return /** @type {HTMLDialogElement} */ (el);
     }
-    if (el.parentElement) {
+    if (el.assignedSlot) {
+      el = el.assignedSlot;
+    } else if (el.parentElement) {
       el = el.parentElement;
     } else if (el.parentNode) {
       el = el.parentNode.host;
diff --git a/dist/dialog-polyfill.js b/dist/dialog-polyfill.js
index aee7d96..c9954d6 100644
--- a/dist/dialog-polyfill.js
+++ b/dist/dialog-polyfill.js
@@ -70,7 +70,9 @@
       if (el.localName === 'dialog') {
         return /** @type {HTMLDialogElement} */ (el);
       }
-      if (el.parentElement) {
+      if (el.assignedSlot) {
+        el = el.assignedSlot;
+      } else if (el.parentElement) {
         el = el.parentElement;
       } else if (el.parentNode) {
         el = el.parentNode.host;
diff --git a/index.js b/index.js
index 8adc5ad..2b2fdcd 100644
--- a/index.js
+++ b/index.js
@@ -65,7 +65,9 @@ function findNearestDialog(el) {
     if (el.localName === 'dialog') {
       return /** @type {HTMLDialogElement} */ (el);
     }
-    if (el.parentElement) {
+    if (el.assignedSlot) {
+      el = el.assignedSlot;
+    } else if (el.parentElement) {
       el = el.parentElement;
     } else if (el.parentNode) {
       el = el.parentNode.host;