diff --git a/packages/dom/src/highlight-range.ts b/packages/dom/src/highlight-range.ts
index 7f76e40..e18a6a4 100644
--- a/packages/dom/src/highlight-range.ts
+++ b/packages/dom/src/highlight-range.ts
@@ -79,9 +79,8 @@
   }
 
   // Collect the text nodes.
-  if (!range.startContainer.ownerDocument)
-    throw new TypeError('range.startContainer lacks an ownerDocument');
-  const walker = range.startContainer.ownerDocument.createTreeWalker(
+  const document = range.startContainer.ownerDocument || range.startContainer as Document;
+  const walker = document.createTreeWalker(
     range.commonAncestorContainer,
     NodeFilter.SHOW_TEXT,
     {
@@ -116,13 +115,13 @@
 }
 
 // Replace [node] with <tagName ...attributes>[node]</tagName>
-function wrapNodeInHighlight(node: Node, tagName: string, attributes: Record<string, string>): HTMLElement {
-  if (!node.ownerDocument) throw new TypeError('Node to be highlighted lacks an ownerDocument');
-  const highlightElement = node.ownerDocument.createElement(tagName);
+function wrapNodeInHighlight(node: ChildNode, tagName: string, attributes: Record<string, string>): HTMLElement {
+  const document = node.ownerDocument as Document;
+  const highlightElement = document.createElement(tagName);
   Object.keys(attributes).forEach(key => {
     highlightElement.setAttribute(key, attributes[key]);
   });
-  const tempRange = node.ownerDocument.createRange();
+  const tempRange = document.createRange();
   tempRange.selectNode(node);
   tempRange.surroundContents(highlightElement);
   return highlightElement;
diff --git a/packages/dom/src/scope.ts b/packages/dom/src/scope.ts
index 24c9b26..e7aec59 100644
--- a/packages/dom/src/scope.ts
+++ b/packages/dom/src/scope.ts
@@ -21,25 +21,21 @@
 import { DomScope } from './types';
 
 export function ownerDocument(scope: DomScope): Document {
-  let document;
-  if ('commonAncestorContainer' in scope)
-    document = scope.commonAncestorContainer.ownerDocument;
-  else
-    document = scope.ownerDocument;
-  if (!document) throw new TypeError('scope lacks an ownerDocument');
-  return document;
+  const node = isRange(scope)
+    ? scope.commonAncestorContainer
+    : scope;
+  return node.ownerDocument || node as Document;
 }
 
 export function rangeFromScope(scope: DomScope): Range {
-  if ('commonAncestorContainer' in scope) {
+  if (isRange(scope)) {
     return scope;
   }
-
-  const document = scope.ownerDocument;
-  if (!document) throw new TypeError('scope lacks an ownerDocument');
-  const range = document.createRange();
-
+  const range = ownerDocument(scope).createRange();
   range.selectNodeContents(scope);
-
   return range;
 }
+
+function isRange(scope: DomScope): scope is Range {
+  return 'collapsed' in scope;
+}