diff --git a/browser/components/sessionstore/test/browser/Makefile.in b/browser/components/sessionstore/test/browser/Makefile.in
index a0b3835672d..1f5bffff223 100644
--- a/browser/components/sessionstore/test/browser/Makefile.in
+++ b/browser/components/sessionstore/test/browser/Makefile.in
@@ -45,8 +45,6 @@ relativesrcdir  = browser/components/sessionstore/test/browser
 include $(DEPTH)/config/autoconf.mk
 include $(topsrcdir)/config/rules.mk
 
-# browser_477657.js is disabled, because it's unreliable (bug 482975).
-
 _BROWSER_TEST_FILES = \
 	browser_248970_a.js \
 	browser_248970_b.js \
@@ -96,6 +94,7 @@ _BROWSER_TEST_FILES = \
 	browser_466937_sample.html \
 	browser_476161.js \
 	browser_476161_sample.html \
+	browser_477657.js \
 	browser_480148.js \
 	browser_480893.js \
 	browser_483330.js \