--- a/layout/style/test/mochitest.ini
+++ b/layout/style/test/mochitest.ini
@@ -284,17 +284,16 @@ skip-if = toolkit == 'android' #bug 7752
 [test_transitions_events.html]
 [test_transitions.html]
 skip-if = (android_version == '18' && debug) # bug 1159532
 [test_transitions_bug537151.html]
 [test_transitions_dynamic_changes.html]
 [test_transitions_per_property.html]
 skip-if = (toolkit == 'android' || stylo) # bug 775227 for android, bug 1292283 for stylo
 [test_transitions_replacement_on_busy_frame.html]
-skip-if = stylo # timeout bug 1328503
 support-files = file_transitions_replacement_on_busy_frame.html
 [test_transitions_step_functions.html]
 [test_transitions_with_disabled_properties.html]
 support-files = file_transitions_with_disabled_properties.html
 [test_unclosed_parentheses.html]
 [test_unicode_range_loading.html]
 skip-if = stylo # bug 1366921
 support-files = ../../reftests/fonts/markA.woff ../../reftests/fonts/markB.woff ../../reftests/fonts/markC.woff ../../reftests/fonts/markD.woff