diff --git a/security/manager/ssl/tests/mochitest/mixedcontent/Makefile.in b/security/manager/ssl/tests/mochitest/mixedcontent/Makefile.in
index d9fb5a70c1c..44a811dc2c5 100644
--- a/security/manager/ssl/tests/mochitest/mixedcontent/Makefile.in
+++ b/security/manager/ssl/tests/mochitest/mixedcontent/Makefile.in
@@ -68,6 +68,7 @@ _TEST_FILES = \
         somestyle.css \
         test_bug383369.html \
         test_bug455367.html \
+        test_bug472986.html \
         test_cssBefore1.html \
         test_cssContent1.html \
         test_cssContent2.html \
@@ -99,7 +100,6 @@ _TEST_FILES = \
 #        test_bug329869.html \  leaks, bug 452401
 #        test_dynUnsecureRedirect.html \ intermitently fails, quit often, bug 487402
 #        test_unsecureIframeMetaRedirect.html \ also intermittently fails, less often, bug 487632
-#        test_bug472986.html \ causes timeout of this and all following tests
 
 
 libs:: $(_TEST_FILES)
diff --git a/testing/mochitest/ssltunnel/ssltunnel.cpp b/testing/mochitest/ssltunnel/ssltunnel.cpp
index ca67e1acea7..dfe771784aa 100644
--- a/testing/mochitest/ssltunnel/ssltunnel.cpp
+++ b/testing/mochitest/ssltunnel/ssltunnel.cpp
@@ -402,9 +402,13 @@ void HandleConnection(void* data)
         PRInt16 &in_flags2 = sockets[s2].in_flags;
         sockets[s].out_flags = 0;
 
-        if (out_flags & PR_POLL_EXCEPT)
+        if (out_flags & (PR_POLL_EXCEPT | PR_POLL_ERR | PR_POLL_HUP))
         {
           client_error = true;
+          // We got a fatal error state on the socket. Clear the output buffer
+          // for this socket to break the main loop, we will never more be able
+          // to send those data anyway.
+          buffers[s2].bufferhead = buffers[s2].buffertail = buffers[s2].buffer;
           continue;
         } // PR_POLL_EXCEPT handling