diff --git a/components/script/dom/node.rs b/components/script/dom/node.rs
index e05bd2b9aa4..cecad5d7b76 100644
--- a/components/script/dom/node.rs
+++ b/components/script/dom/node.rs
@@ -280,7 +280,9 @@ impl Node {
 
         new_child.parent_node.set(Some(self));
         if let Some(shadow_root) = self.downcast::<ShadowRoot>() {
-            new_child.composed_parent_node.set(Some(shadow_root.Host().upcast::<Node>()));
+            new_child
+                .composed_parent_node
+                .set(Some(shadow_root.Host().upcast::<Node>()));
         } else {
             new_child.composed_parent_node.set(Some(self));
         }
@@ -2528,8 +2530,11 @@ impl NodeMethods for Node {
     }
 
     // https://dom.spec.whatwg.org/#dom-node-clonenode
-    fn CloneNode(&self, deep: bool) -> DomRoot<Node> {
-        Node::clone(
+    fn CloneNode(&self, deep: bool) -> Fallible<DomRoot<Node>> {
+        if deep && self.is::<ShadowRoot>() {
+            return Err(Error::NotSupported);
+        }
+        Ok(Node::clone(
             self,
             None,
             if deep {
@@ -2537,7 +2542,7 @@ impl NodeMethods for Node {
             } else {
                 CloneChildrenFlag::DoNotCloneChildren
             },
-        )
+        ))
     }
 
     // https://dom.spec.whatwg.org/#dom-node-isequalnode
diff --git a/components/script/dom/range.rs b/components/script/dom/range.rs
index 96f276944bc..afa759de52f 100644
--- a/components/script/dom/range.rs
+++ b/components/script/dom/range.rs
@@ -500,7 +500,7 @@ impl RangeMethods for Range {
                 fragment.upcast::<Node>().AppendChild(&clone)?;
             } else {
                 // Step 14.1.
-                let clone = child.CloneNode(false);
+                let clone = child.CloneNode(/* deep */ false)?;
                 // Step 14.2.
                 fragment.upcast::<Node>().AppendChild(&clone)?;
                 // Step 14.3.
@@ -521,7 +521,7 @@ impl RangeMethods for Range {
         // Step 15.
         for child in contained_children {
             // Step 15.1.
-            let clone = child.CloneNode(true);
+            let clone = child.CloneNode(/* deep */ true)?;
             // Step 15.2.
             fragment.upcast::<Node>().AppendChild(&clone)?;
         }
@@ -537,7 +537,7 @@ impl RangeMethods for Range {
                 fragment.upcast::<Node>().AppendChild(&clone)?;
             } else {
                 // Step 17.1.
-                let clone = child.CloneNode(false);
+                let clone = child.CloneNode(/* deep */ false)?;
                 // Step 17.2.
                 fragment.upcast::<Node>().AppendChild(&clone)?;
                 // Step 17.3.
@@ -573,7 +573,7 @@ impl RangeMethods for Range {
         if end_node == start_node {
             if let Some(end_data) = end_node.downcast::<CharacterData>() {
                 // Step 4.1.
-                let clone = end_node.CloneNode(true);
+                let clone = end_node.CloneNode(/* deep */ true)?;
                 // Step 4.2.
                 let text = end_data.SubstringData(start_offset, end_offset - start_offset);
                 clone
@@ -614,7 +614,7 @@ impl RangeMethods for Range {
             if let Some(start_data) = child.downcast::<CharacterData>() {
                 assert!(child == start_node);
                 // Step 15.1.
-                let clone = start_node.CloneNode(true);
+                let clone = start_node.CloneNode(/* deep */ true)?;
                 // Step 15.2.
                 let text = start_data.SubstringData(start_offset, start_node.len() - start_offset);
                 clone
@@ -631,7 +631,7 @@ impl RangeMethods for Range {
                 )?;
             } else {
                 // Step 16.1.
-                let clone = child.CloneNode(false);
+                let clone = child.CloneNode(/* deep */ false)?;
                 // Step 16.2.
                 fragment.upcast::<Node>().AppendChild(&clone)?;
                 // Step 16.3.
@@ -658,7 +658,7 @@ impl RangeMethods for Range {
             if let Some(end_data) = child.downcast::<CharacterData>() {
                 assert!(child == end_node);
                 // Step 18.1.
-                let clone = end_node.CloneNode(true);
+                let clone = end_node.CloneNode(/* deep */ true)?;
                 // Step 18.2.
                 let text = end_data.SubstringData(0, end_offset);
                 clone
@@ -671,7 +671,7 @@ impl RangeMethods for Range {
                 end_data.ReplaceData(0, end_offset, DOMString::new())?;
             } else {
                 // Step 19.1.
-                let clone = child.CloneNode(false);
+                let clone = child.CloneNode(/* deep */ false)?;
                 // Step 19.2.
                 fragment.upcast::<Node>().AppendChild(&clone)?;
                 // Step 19.3.
diff --git a/components/script/dom/webidls/Node.webidl b/components/script/dom/webidls/Node.webidl
index 479bec28a1f..9433e96efa2 100644
--- a/components/script/dom/webidls/Node.webidl
+++ b/components/script/dom/webidls/Node.webidl
@@ -58,7 +58,7 @@ interface Node : EventTarget {
   [CEReactions]
   void normalize();
 
-  [CEReactions]
+  [CEReactions, Throws]
   Node cloneNode(optional boolean deep = false);
   [Pure]
   boolean isEqualNode(Node? node);