diff --git a/testing/web-platform/meta/media-source/mediasource-duration.html.ini b/testing/web-platform/meta/media-source/mediasource-duration.html.ini
index bc555511abf..019c42da94d 100644
--- a/testing/web-platform/meta/media-source/mediasource-duration.html.ini
+++ b/testing/web-platform/meta/media-source/mediasource-duration.html.ini
@@ -5,13 +5,22 @@
     if os == "mac": OK
     TIMEOUT
   [Test seek starts on duration truncation below currentTime]
-    disabled: TIMEOUT or FAIL https://bugzilla.mozilla.org/show_bug.cgi?id=1085247
+    expected:
+      if (os == "win") and (version != "5.1.2600"): FAIL
+      if os == "mac": FAIL
+      TIMEOUT
 
   [Test appendBuffer completes previous seek to truncated duration]
-    disabled: TIMEOUT or FAIL https://bugzilla.mozilla.org/show_bug.cgi?id=1085247
+    expected:
+      if (os == "win") and (version != "5.1.2600"): FAIL
+      if os == "mac": FAIL
+      TIMEOUT
 
   [Test endOfStream completes previous seek to truncated duration]
-    disabled: TIMEOUT or FAIL https://bugzilla.mozilla.org/show_bug.cgi?id=1085247
+    expected:
+      if (os == "win") and (version != "5.1.2600"): FAIL
+      if os == "mac": FAIL
+      TIMEOUT
 
   [Test setting same duration multiple times does not fire duplicate durationchange]
     expected: FAIL