diff --git a/mozilla/layout/reftests/first-letter/379799-1-ref.html b/mozilla/layout/reftests/first-letter/379799-1-ref.html
new file mode 100644
index 00000000000..56c66e1bbee
--- /dev/null
+++ b/mozilla/layout/reftests/first-letter/379799-1-ref.html
@@ -0,0 +1,10 @@
+<!DOCTYPE html>
+<html>
+<body>
+
+<div class="fl" id="parent" style="color: green">
+  Foo <span id="test">Bar</span>
+</div>
+
+</body>
+</html>
diff --git a/mozilla/layout/reftests/first-letter/379799-1.html b/mozilla/layout/reftests/first-letter/379799-1.html
new file mode 100644
index 00000000000..532b26407c1
--- /dev/null
+++ b/mozilla/layout/reftests/first-letter/379799-1.html
@@ -0,0 +1,29 @@
+<!DOCTYPE html>
+<html>
+<head>
+
+<style id="firstLetterSheet">
+  .fl:first-letter { color: red }
+</style>
+
+<script>
+
+function boom()
+{
+  document.getElementById("parent").className = "";
+  document.body.offsetWidth;
+  document.getElementById("test").style.position = "relative";
+}
+
+</script>
+
+</head>
+
+<body onload="boom()">
+
+<div class="fl" id="parent" style="color: green">
+  Foo <span id="test">Bar</span>
+</div>
+
+</body>
+</html>
diff --git a/mozilla/layout/reftests/first-letter/reftest.list b/mozilla/layout/reftests/first-letter/reftest.list
index 76fe0ca2aed..34a8442bfb5 100644
--- a/mozilla/layout/reftests/first-letter/reftest.list
+++ b/mozilla/layout/reftests/first-letter/reftest.list
@@ -30,3 +30,4 @@ random == dynamic-3b.html dynamic-3-ref.html
 == 23605-6.html 23605-6-ref.html
 random-if(MOZ_WIDGET_TOOLKIT=="gtk2") == 329069-1.html 329069-1-ref.html # failure is font-dependent, may be related to bug 404848
 == 342120-1.xhtml 342120-1-ref.xhtml
+== 379799-1.html 379799-1-ref.html
