--- a/layout/reftests/w3c-css/submitted/reftest.list
+++ b/layout/reftests/w3c-css/submitted/reftest.list
@@ -48,17 +48,19 @@ include multicol3/reftest.list
 
 # Ruby Layout Module
 include ruby/reftest.list
 
 # Selectors Level 4
 include selectors4/reftest.list
 
 # Shapes Level 1
-include shapes1/reftest.list
+# Bug 1300355: Skip shapes reftests to prevent frequent intermittent failures
+# on Win7 debug.
+skip-if(winWidget&&isDebugBuild) include shapes1/reftest.list
 
 # Text Level 3
 # After Bug 1316482, we've added a large number of tests in this folder, which
 # indirectly causes frequent reftest failures on win7 debug. (see Bug 1300355)
 # Since the root cause is not these tests, skip them on win7 debug for now.
 # Once we come up with a better solution, we should re-enable this folder on
 # win7 debug.
 skip-if(winWidget&&isDebugBuild) include text3/reftest.list