diff --git a/Lib/test/test_trace.py b/Lib/test/test_trace.py
index 9266280..d2d15f2 100644
--- a/Lib/test/test_trace.py
+++ b/Lib/test/test_trace.py
@@ -245,6 +245,8 @@
         }
         self.assertEqual(self.tracer.results().calledfuncs, expected)
 
+    @unittest.skipIf(hasattr(sys, 'gettrace') and sys.gettrace(),
+                     'pre-existing trace function throws off measurements')
     def test_inst_method_calling(self):
         obj = TracedClass(20)
         self.tracer.runfunc(obj.inst_method_calling, 1)
@@ -264,6 +266,8 @@
         self.tracer = Trace(count=0, trace=0, countcallers=1)
         self.filemod = my_file_and_modname()
 
+    @unittest.skipIf(hasattr(sys, 'gettrace') and sys.gettrace(),
+                     'pre-existing trace function throws off measurements')
     def test_loop_caller_importing(self):
         self.tracer.runfunc(traced_func_importing_caller, 1)