diff --git a/layout/reftests/css-animations/no-style-sharing-with-animations-ref.html b/layout/reftests/css-animations/no-style-sharing-with-animations-ref.html
new file mode 100644
index 000000000000..0218b02f8acd
--- /dev/null
+++ b/layout/reftests/css-animations/no-style-sharing-with-animations-ref.html
@@ -0,0 +1,11 @@
+<!DOCTYPE html>
+<html>
+<style>
+div {
+  background-color: green;
+  width: 100px;
+  height: 100px;
+}
+</style>
+<div></div>
+<div></div>
diff --git a/layout/reftests/css-animations/no-style-sharing-with-animations.html b/layout/reftests/css-animations/no-style-sharing-with-animations.html
new file mode 100644
index 000000000000..02dc960ca2ba
--- /dev/null
+++ b/layout/reftests/css-animations/no-style-sharing-with-animations.html
@@ -0,0 +1,26 @@
+<!DOCTYPE html>
+<html class="reftest-wait">
+<style>
+.animation {
+  animation: anim 100s forwards;
+}
+@keyframes anim {
+  0% { background-color: red; }
+  100% { background-color: red; }
+}
+div {
+  background-color: green;
+  width: 100px;
+  height: 100px;
+}
+</style>
+<div class="animation"></div>
+<div class="animation"></div>
+<script>
+document.addEventListener('MozReftestInvalidate', () => {
+  requestAnimationFrame(() => {
+    document.styleSheets[0].cssRules[0].style.animationName = 'none';
+    document.documentElement.classList.remove('reftest-wait');
+  });
+}, false);
+</script>
diff --git a/layout/reftests/css-animations/reftest.list b/layout/reftests/css-animations/reftest.list
index ab1ed3dfacb8..c25073273a66 100644
--- a/layout/reftests/css-animations/reftest.list
+++ b/layout/reftests/css-animations/reftest.list
@@ -60,3 +60,4 @@ fails == background-position-important.html background-position-ref.html # This
 == change-animation-name-to-none-in-rule.html change-animation-name-in-rule-ref.html
 == change-animation-name-to-other-in-rule.html change-animation-name-in-rule-ref.html
 == change-animation-name-to-non-existent-in-rule.html change-animation-name-in-rule-ref.html
+== no-style-sharing-with-animations.html no-style-sharing-with-animations-ref.html
