diff --git a/lib/cockpit.pm b/lib/cockpit.pm
index 50e7ce5c..227811b6 100644
--- a/lib/cockpit.pm
+++ b/lib/cockpit.pm
@@ -19,6 +19,7 @@ sub start_cockpit {
     # https://bugzilla.redhat.com/show_bug.cgi?id=1439429
     assert_script_run "sed -i -e 's,enable_xauth=1,enable_xauth=0,g' /usr/bin/startx";
     disable_firefox_studies;
+    assert_script_run "export MOZ_LOG_FILE=/tmp/firefox.log";
     # run firefox directly in X as root. never do this, kids!
     type_string "startx /usr/bin/firefox -width 1024 -height 768 http://localhost:9090\n";
     assert_screen "cockpit_login", 60;
diff --git a/lib/freeipa.pm b/lib/freeipa.pm
index ed64b032..59308f8f 100644
--- a/lib/freeipa.pm
+++ b/lib/freeipa.pm
@@ -42,6 +42,7 @@ sub start_webui {
     # https://bugzilla.redhat.com/show_bug.cgi?id=1439429
     assert_script_run "sed -i -e 's,enable_xauth=1,enable_xauth=0,g' /usr/bin/startx";
     disable_firefox_studies;
+    assert_script_run "export MOZ_LOG_FILE=/tmp/firefox.log";
     type_string "startx /usr/bin/firefox -width 1024 -height 768 https://ipa001.test.openqa.fedoraproject.org\n";
     assert_screen ["freeipa_webui_login", $user_screen], 60;
     wait_still_screen(stilltime => 5, similarity_level => 45);
diff --git a/lib/installedtest.pm b/lib/installedtest.pm
index 703f2301..b2cc3886 100644
--- a/lib/installedtest.pm
+++ b/lib/installedtest.pm
@@ -120,6 +120,11 @@ sub post_fail_hook {
         upload_logs "/var/lib/pgsql/initdb_postgresql.log";
     }
 
+    # update Firefox default log (for startx firefox tests)
+    unless (script_run 'test -f /tmp/firefox.log') {
+        upload_logs "/tmp/firefox.log";
+    }
+
     # Upload /var/log
     # lastlog can mess up tar sometimes and it's not much use
     unless (script_run "tar czvf /tmp/var_log.tar.gz --exclude='lastlog' /var/log") {