diff --git a/tests/run-tests.py b/tests/run-tests.py
--- a/tests/run-tests.py
+++ b/tests/run-tests.py
@@ -2015,11 +2015,11 @@ class TestRunner(object):
     def _getport(self, count):
         port = self._ports.get(count) # do we have a cached entry?
         if port is None:
-            port = self.options.port + self._portoffset
             portneeded = 3
             # above 100 tries we just give up and let test reports failure
             for tries in xrange(100):
                 allfree = True
+                port = self.options.port + self._portoffset
                 for idx in xrange(portneeded):
                     if not checkportisavailable(port + idx):
                         allfree = False
diff --git a/tests/test-run-tests.t b/tests/test-run-tests.t
--- a/tests/test-run-tests.t
+++ b/tests/test-run-tests.t
@@ -223,6 +223,20 @@ Verify that when a process fails to star
   [1]
   $ rm test-serve-fail.t
 
+Verify that we can try other ports
+===================================
+  $ hg init inuse
+  $ hg serve -R inuse -p $HGPORT -d --pid-file=blocks.pid
+  $ cat blocks.pid >> $DAEMON_PIDS
+  $ cat > test-serve-inuse.t <<EOF
+  >   $ hg serve -R `pwd`/inuse -p \$HGPORT -d --pid-file=hg.pid
+  >   $ cat hg.pid >> \$DAEMON_PIDS
+  > EOF
+  $ rt test-serve-inuse.t
+  .
+  # Ran 1 tests, 0 skipped, 0 warned, 0 failed.
+  $ rm test-serve-inuse.t
+
 Running In Debug Mode
 ======================