diff --git a/security/manager/ssl/tests/unit/test_ocsp_timeout.js b/security/manager/ssl/tests/unit/test_ocsp_timeout.js
index 1a763f1da57..7a7aca4a9a0 100644
--- a/security/manager/ssl/tests/unit/test_ocsp_timeout.js
+++ b/security/manager/ssl/tests/unit/test_ocsp_timeout.js
@@ -24,10 +24,6 @@ let gSocketListener = {
   onStopListening: function(serverSocket, socketTransport) {}
 };
 
-const ua = Cc["@mozilla.org/network/protocol;1?name=http"]
-             .getService(Ci.nsIHttpProtocolHandler).userAgent;
-const gIsWinXP = ua.indexOf("Windows NT 5.1") != -1;
-
 function run_test() {
   do_get_profile();
 
@@ -60,12 +56,10 @@ function add_tests_in_mode(useHardFail) {
   // Reset state
   add_test(function() {
     let endTime = new Date();
-    // With OCSP hard-fail on, we timeout after 10 seconds (except if the
-    // OS is Windows XP, which occasionally times out too quickly for reasons
-    // unknown).
+    // With OCSP hard-fail on, we timeout after 10 seconds.
     // With OCSP soft-fail, we timeout after 2 seconds.
     if (useHardFail) {
-      do_check_true((endTime - startTime) > 10000 || gIsWinXP);
+      do_check_true((endTime - startTime) > 10000);
     } else {
       do_check_true((endTime - startTime) > 2000);
     }
diff --git a/security/manager/ssl/tests/unit/xpcshell.ini b/security/manager/ssl/tests/unit/xpcshell.ini
index 24da770bae1..40f40531060 100644
--- a/security/manager/ssl/tests/unit/xpcshell.ini
+++ b/security/manager/ssl/tests/unit/xpcshell.ini
@@ -52,7 +52,8 @@ skip-if = os == "android"
 [test_ocsp_timeout.js]
 run-sequentially = hardcoded ports
 # Bug 1009158: this test times out on Android
-skip-if = os == "android"
+# Bug 1005266: intermittent failures on Windows
+skip-if = os == "android" || os == "win"
 [test_cert_signatures.js]
 [test_ev_certs.js]
 run-sequentially = hardcoded ports