diff --git a/layout/reftests/bugs/433700-ref.html b/layout/reftests/bugs/433700-ref.html
index f341a0377fd..60879fca40f 100644
--- a/layout/reftests/bugs/433700-ref.html
+++ b/layout/reftests/bugs/433700-ref.html
@@ -3,7 +3,7 @@
     <title>Testcase for bug 433700</title>
     <style type="text/css">
 
-body { font-size: 16px; }
+body { font-family: sans-serif; font-size: 16px; }
 
 fieldset,legend { padding:0; margin:0; border-width:0; border-style:solid; }
 fieldset { border-right:7px solid blue; font-size: 16px; }
diff --git a/layout/reftests/bugs/433700.html b/layout/reftests/bugs/433700.html
index 7d13d5ff043..e369dd994f6 100644
--- a/layout/reftests/bugs/433700.html
+++ b/layout/reftests/bugs/433700.html
@@ -3,7 +3,7 @@
     <title>Testcase for bug 433700</title>
     <style type="text/css">
 
-body { font-size: 16px; }
+body { font-family: sans-serif; font-size: 16px; }
 
 fieldset,legend { padding:0; margin:0; border-width:0; border-style:solid; }
 fieldset { border-right:7px solid blue; font-size: 16px; }