diff --git a/tests/run-tests.py b/tests/run-tests.py
--- a/tests/run-tests.py
+++ b/tests/run-tests.py
@@ -321,7 +321,7 @@
 if 'java' in sys.platform:
     IMPL_PATH = b'JYTHONPATH'
 
-defaults = {
+default_defaults = {
     'jobs': ('HGTEST_JOBS', multiprocessing.cpu_count()),
     'timeout': ('HGTEST_TIMEOUT', 180),
     'slowtimeout': ('HGTEST_SLOWTIMEOUT', 1500),
@@ -329,6 +329,8 @@
     'shell': ('HGTEST_SHELL', 'sh'),
 }
 
+defaults = default_defaults.copy()
+
 
 def canonpath(path):
     return os.path.realpath(os.path.expanduser(path))
@@ -1327,6 +1329,9 @@
         env['TESTTMP'] = _bytes2sys(self._testtmp)
         env['TESTNAME'] = self.name
         env['HOME'] = _bytes2sys(self._testtmp)
+        formated_timeout = _bytes2sys(b"%d" % default_defaults['timeout'][1])
+        env['HGTEST_TIMEOUT_DEFAULT'] = formated_timeout
+        env['HGTEST_TIMEOUT'] = _bytes2sys(b"%d" % self._timeout)
         # This number should match portneeded in _getport
         for port in xrange(3):
             # This list should be parallel to _portmap in _getreplacements
diff --git a/tests/testlib/wait-on-file b/tests/testlib/wait-on-file
--- a/tests/testlib/wait-on-file
+++ b/tests/testlib/wait-on-file
@@ -10,6 +10,12 @@
 fi
 
 timer="$1"
+
+# if the test timeout have been extended, explicitly extend the provided timer
+if [ "$HGTEST_TIMEOUT_DEFAULT" -lt "$HGTEST_TIMEOUT" ]; then
+    timer=$(( ("$timer" * "$HGTEST_TIMEOUT") / $HGTEST_TIMEOUT_DEFAULT ))
+fi
+
 wait_on="$2"
 create=""
 if [ $# -eq 3 ]; then