diff --git a/layout/xul/base/src/grid/crashtests/423802-crash.xul b/layout/xul/base/src/grid/crashtests/423802-crash.xul
new file mode 100644
index 00000000000..0ae4eab8f07
--- /dev/null
+++ b/layout/xul/base/src/grid/crashtests/423802-crash.xul
@@ -0,0 +1,13 @@
+<?xml version="1.0"?>
+
+<window xmlns  = "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+
+<grid>
+  <columns>
+    <column id="col1" flex="1"/>
+  <column id="col2" flex="1"/>
+    <column id="col3" flex="P-2"/>
+  </columns>
+</grid>
+
+</window>
diff --git a/layout/xul/base/src/grid/crashtests/crashtests.list b/layout/xul/base/src/grid/crashtests/crashtests.list
index 3397623c10d..7f6b9900012 100644
--- a/layout/xul/base/src/grid/crashtests/crashtests.list
+++ b/layout/xul/base/src/grid/crashtests/crashtests.list
@@ -5,3 +5,4 @@ load 321066-1.xul
 load 321073-1.xul
 load 382750-1.xul
 load 400790-1.xul
+load 423802-crash.xul