diff --git a/src/components/script/dom/document.rs b/src/components/script/dom/document.rs
index 25768e938cc..e6f0a15fb23 100644
--- a/src/components/script/dom/document.rs
+++ b/src/components/script/dom/document.rs
@@ -153,6 +153,7 @@ impl<'a> DocumentHelpers for JSRef<'a, Document> {
             let node: &JSRef<Node> = NodeCast::from_ref(element);
             node.is_in_doc()
         });
+        assert!(!id.is_empty());
 
         let mut idmap = self.idmap.deref().borrow_mut();
 
diff --git a/src/components/script/dom/element.rs b/src/components/script/dom/element.rs
index 354d6a66a1b..5bf72216d96 100644
--- a/src/components/script/dom/element.rs
+++ b/src/components/script/dom/element.rs
@@ -832,7 +832,7 @@ impl<'a> VirtualMethods for JSRef<'a, Element> {
             }
             "id" => {
                 let node: &JSRef<Node> = NodeCast::from_ref(self);
-                if node.is_in_doc() {
+                if node.is_in_doc() && !value.is_empty() {
                     let doc = document_from_node(self).root();
                     doc.register_named_element(self, value.clone());
                 }
@@ -855,7 +855,7 @@ impl<'a> VirtualMethods for JSRef<'a, Element> {
             }
             "id" => {
                 let node: &JSRef<Node> = NodeCast::from_ref(self);
-                if node.is_in_doc() {
+                if node.is_in_doc() && !value.is_empty() {
                     let doc = document_from_node(self).root();
                     doc.unregister_named_element(self, value);
                 }
@@ -885,7 +885,10 @@ impl<'a> VirtualMethods for JSRef<'a, Element> {
         match self.get_attribute(Null, "id").root() {
             Some(attr) => {
                 let doc = document_from_node(self).root();
-                doc.deref().register_named_element(self, attr.deref().Value());
+                let value = attr.deref().Value();
+                if !value.is_empty() {
+                    doc.deref().register_named_element(self, value);
+                }
             }
             _ => ()
         }
@@ -902,7 +905,10 @@ impl<'a> VirtualMethods for JSRef<'a, Element> {
         match self.get_attribute(Null, "id").root() {
             Some(attr) => {
                 let doc = document_from_node(self).root();
-                doc.deref().unregister_named_element(self, attr.deref().Value());
+                let value = attr.deref().Value();
+                if !value.is_empty() {
+                    doc.deref().unregister_named_element(self, value);
+                }
             }
             _ => ()
         }
diff --git a/src/test/wpt/metadata/dom/nodes/Document-getElementById.html.ini b/src/test/wpt/metadata/dom/nodes/Document-getElementById.html.ini
index 86756aed37c..48c78eda0d5 100644
--- a/src/test/wpt/metadata/dom/nodes/Document-getElementById.html.ini
+++ b/src/test/wpt/metadata/dom/nodes/Document-getElementById.html.ini
@@ -1,8 +1,5 @@
 [Document-getElementById.html]
   type: testharness
-  [Calling document.getElementById with an empty string argument.]
-    expected: FAIL
-
   [add id attribute via innerHTML]
     expected: FAIL