diff --git a/layout/reftests/bugs/1374062-ref.html b/layout/reftests/bugs/1374062-ref.html
new file mode 100644
index 000000000000..e8b74a077a4a
--- /dev/null
+++ b/layout/reftests/bugs/1374062-ref.html
@@ -0,0 +1,8 @@
+<!doctype html>
+<title>CSS Test reference</title>
+<style>
+  div { color: green; font-size: 10px; }
+</style>
+<div>
+  Should be green, and have a 10px font-size.
+</div>
diff --git a/layout/reftests/bugs/1374062.html b/layout/reftests/bugs/1374062.html
new file mode 100644
index 000000000000..33c53b272919
--- /dev/null
+++ b/layout/reftests/bugs/1374062.html
@@ -0,0 +1,16 @@
+<!doctype html>
+<title>
+  Test for bug 1374062: We don't update the root font-size just because the
+  element has no parent element.
+</title>
+<style>
+  :root { font-size: 5px; }
+  [restyled] { color: green; font-size: 2rem; }
+</style>
+<div>
+  Should be green, and have a 10px font-size.
+</div>
+<script>
+  getComputedStyle(document.createElement('div')).color;
+  document.querySelector('div').setAttribute("restyled", "");
+</script>
diff --git a/layout/reftests/bugs/reftest.list b/layout/reftests/bugs/reftest.list
index 72c458abd894..77ee93dfb7c1 100644
--- a/layout/reftests/bugs/reftest.list
+++ b/layout/reftests/bugs/reftest.list
@@ -2015,3 +2015,4 @@ fails-if(!stylo||styloVsGecko) == 1365162-1.html 1365162-1-ref.html
 == 1369954-1.xhtml 1369954-1-ref.xhtml
 == 1369985-1.html 1369985-1-ref.html
 == 1371130.xhtml 1371130-ref.xhtml
+== 1374062.html 1374062-ref.html
