diff --git a/layout/reftests/css-break/reftest.list b/layout/reftests/css-break/reftest.list
index 982b51476fa6..28f60935b9c0 100644
--- a/layout/reftests/css-break/reftest.list
+++ b/layout/reftests/css-break/reftest.list
@@ -10,3 +10,4 @@ fuzzy-if(!Android,1,62) fuzzy-if(Android,8,6627) == box-decoration-break-first-l
 == box-decoration-break-with-bidi.html box-decoration-break-with-bidi-ref.html
 == box-decoration-break-bug-1235152.html box-decoration-break-bug-1235152-ref.html
 == box-decoration-break-bug-1249913.html box-decoration-break-bug-1249913-ref.html
+== vertical-wm-001.html vertical-wm-001-ref.html
diff --git a/layout/reftests/css-break/vertical-wm-001-ref.html b/layout/reftests/css-break/vertical-wm-001-ref.html
new file mode 100644
index 000000000000..513de3cf1ca4
--- /dev/null
+++ b/layout/reftests/css-break/vertical-wm-001-ref.html
@@ -0,0 +1,90 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: splitting vertical writing-mode blocks</title>
+  <link rel="author" title="Mats Palmgren" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1328095">
+<style type="text/css">
+body,html { padding:30px; margin:0; }
+.col {
+     -moz-columns: 2;
+  -webkit-columns: 2;
+          columns: 2;
+     -moz-column-gap: 0;
+  -webkit-column-gap: 0;
+          column-gap: 0;
+     -moz-column-fill: auto;
+  -webkit-column-fill: auto;
+          column-fill: auto;
+
+  width: 90px;
+  height: 140px;
+  border:1px solid;
+}
+.vl { writing-mode: vertical-lr; }
+
+.c {
+  width: 90px;
+  height: 140px;
+  writing-mode: vertical-lr;
+  border:1px solid;
+}
+
+x {
+  display:block;
+  break-inside:avoid;
+  page-break-inside:avoid;
+  vertical-align: top;
+  width:20px; height:20px;
+  background:silver;
+}
+x:nth-of-type(2n) {background:purple;}
+
+.h {
+  width: 140px;
+  height: 90px;
+}
+.h x { display:block; }
+blue { display:block; height: 70px; border-left:25px solid blue; }
+grey { display:block; height: 70px; border-left:17px solid grey; }
+.h blue { display:block; height: auto; border-top:25px solid blue; }
+.h grey { display:block; height: auto; border-top:17px solid grey; }
+</style>
+</head>
+<body>
+
+<div class="col vl">
+<div class="inner" style="margin-left:40px"></div>
+<blue></blue>
+<x></x><x></x>
+<grey></grey>
+</div>
+
+<div class="col h">
+<div class="inner" style="margin-top:40px"></div>
+<blue></blue>
+<x></x><x></x>
+<grey></grey>
+</div>
+
+<div class="col vl">
+<div class="inner" style="margin-left:40px"></div>
+<blue></blue>
+<x></x><x></x>
+<div style="width:45px"></div>
+<grey></grey>
+</div>
+
+<div class="col vl">
+<div class="inner" style="margin-left:40px"></div>
+<blue></blue>
+<x></x><x></x>
+<div style="width:60px"></div>
+<grey></grey>
+</div>
+
+</body>
+</html>
diff --git a/layout/reftests/css-break/vertical-wm-001.html b/layout/reftests/css-break/vertical-wm-001.html
new file mode 100644
index 000000000000..6cd0ce545563
--- /dev/null
+++ b/layout/reftests/css-break/vertical-wm-001.html
@@ -0,0 +1,96 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Testcase: splitting vertical writing-mode blocks</title>
+  <link rel="author" title="Mats Palmgren" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1328095">
+  <link rel="help" href="http://dev.w3.org/csswg/css-break/#break-decoration">
+  <link rel="help" href="https://drafts.csswg.org/css-writing-modes-3/">
+  <link rel="match" href="vertical-wm-001-ref.html">
+<style type="text/css">
+body,html { padding:30px; margin:0; }
+.col {
+     -moz-columns: 2;
+  -webkit-columns: 2;
+          columns: 2;
+     -moz-column-gap: 0;
+  -webkit-column-gap: 0;
+          column-gap: 0;
+     -moz-column-fill: auto;
+  -webkit-column-fill: auto;
+          column-fill: auto;
+
+  width: 90px;
+  height: 140px;
+  border:1px solid;
+}
+.vl { writing-mode: vertical-lr; }
+
+.c {
+  width: 90px;
+  height: 140px;
+  writing-mode: vertical-lr;
+  border:1px solid;
+}
+
+.inner {
+  border-left:25px solid blue;
+  border-right:17px solid grey;
+  height: 70px;
+}
+
+x {
+  display:block;
+  break-inside:avoid;
+  page-break-inside:avoid;
+  vertical-align: top;
+  width:20px; height:20px;
+  background:silver;
+}
+x:nth-of-type(2n) {background:purple;}
+
+.h {
+  width: 140px;
+  height: 90px;
+}
+.h x { display:block; }
+.h .inner {
+  border:none;
+  border-top:25px solid blue;
+  border-bottom:17px solid grey;
+  width: 70px;
+  height: auto;
+}
+</style>
+</head>
+<body>
+
+<div class="col vl">
+<div class="inner" style="margin-left:40px">
+<x></x><x></x>
+</div>
+</div>
+
+<div class="col h">
+<div class="inner" style="margin-top:40px">
+<x></x><x></x>
+</div>
+</div>
+
+<div class="col vl">
+<div class="inner" style="margin-left:40px; width:90px">
+<x></x><x></x>
+</div>
+</div>
+
+<div class="col vl">
+<div class="inner" style="margin-left:40px; width:100px">
+<x></x><x></x>
+</div>
+</div>
+
+</body>
+</html>
