diff --git a/components/script/dom/servoparser/mod.rs b/components/script/dom/servoparser/mod.rs
index 531f13274e6..3904910d3a3 100644
--- a/components/script/dom/servoparser/mod.rs
+++ b/components/script/dom/servoparser/mod.rs
@@ -657,7 +657,12 @@ fn insert(parent: &Node, reference_child: Option<&Node>, child: NodeOrText<JS<No
             parent.InsertBefore(&n, reference_child).unwrap();
         },
         NodeOrText::AppendText(t) => {
-            if let Some(text) = parent.GetLastChild().and_then(Root::downcast::<Text>) {
+            let text = reference_child
+                .and_then(Node::GetPreviousSibling)
+                .or_else(|| parent.GetLastChild())
+                .and_then(Root::downcast::<Text>);
+
+            if let Some(text) = text {
                 text.upcast::<CharacterData>().append_data(&t);
             } else {
                 let text = Text::new(String::from(t).into(), &parent.owner_doc());
diff --git a/tests/wpt/metadata/html/syntax/parsing/html5lib_template.html.ini b/tests/wpt/metadata/html/syntax/parsing/html5lib_template.html.ini
deleted file mode 100644
index d07885da2f9..00000000000
--- a/tests/wpt/metadata/html/syntax/parsing/html5lib_template.html.ini
+++ /dev/null
@@ -1,12 +0,0 @@
-[html5lib_template.html?run_type=write]
-  type: testharness
-
-[html5lib_template.html?run_type=write_single]
-  type: testharness
-  [html5lib_template.html 574a95fc9c9f2de3aeaa0c9ee1e6967fc3d4770d]
-    expected: FAIL
-    bug: https://github.com/servo/servo/issues/15979
-
-
-[html5lib_template.html?run_type=uri]
-  type: testharness