--- a/testing/marionette/client/marionette_driver/marionette.py
+++ b/testing/marionette/client/marionette_driver/marionette.py
@@ -1701,26 +1701,25 @@ class Marionette(object):
             marionette.execute_script("global.test1 = 'foo';")
             result = self.marionette.execute_script("return global.test1;", new_sandbox=False)
             assert result == "foo"
 
         """
         args = self._to_json(script_args)
         stack = traceback.extract_stack()
         frame = stack[-2:-1][0]  # grab the second-to-last frame
+        filename = frame[0] if sys.platform == "win32" else os.path.relpath(frame[0])
         body = {"script": script.strip(),
                 "args": args,
                 "newSandbox": new_sandbox,
                 "sandbox": sandbox,
                 "scriptTimeout": script_timeout,
                 "line": int(frame[1]),
-                "filename": os.path.basename(frame[0])}
-
-        rv = self._send_message("WebDriver:ExecuteScript",
-                                body, key="value")
+                "filename": filename}
+        rv = self._send_message("WebDriver:ExecuteScript", body, key="value")
         return self._from_json(rv)
 
     def execute_async_script(self, script, script_args=(), new_sandbox=True,
                              sandbox="default", script_timeout=None,
                              debug_script=False):
         """Executes an asynchronous JavaScript script, and returns the
         result (or None if the script does return a value).
 
@@ -1751,23 +1750,24 @@ class Marionette(object):
                 marionetteScriptFinished(1);
               }, 5000);
             ''')
             assert result == 1
         """
         args = self._to_json(script_args)
         stack = traceback.extract_stack()
         frame = stack[-2:-1][0]  # grab the second-to-last frame
+        filename = frame[0] if sys.platform == "win32" else os.path.relpath(frame[0])
         body = {"script": script.strip(),
                 "args": args,
                 "newSandbox": new_sandbox,
                 "sandbox": sandbox,
                 "scriptTimeout": script_timeout,
                 "line": int(frame[1]),
-                "filename": os.path.basename(frame[0]),
+                "filename": filename,
                 "debug_script": debug_script}
 
         rv = self._send_message("WebDriver:ExecuteAsyncScript",
                                 body, key="value")
         return self._from_json(rv)
 
     def find_element(self, method, target, id=None):
         """Returns an :class:`~marionette_driver.marionette.HTMLElement`