diff --git a/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/wptcommandline.py b/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/wptcommandline.py
index 5d44df2fad9..65a09d5c53b 100644
--- a/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/wptcommandline.py
+++ b/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/wptcommandline.py
@@ -280,8 +280,10 @@ def exe_path(name):
         return
 
     path = find_executable(name)
-    if os.access(path, os.X_OK):
+    if path and os.access(path, os.X_OK):
         return path
+    else:
+        return None
 
 
 def check_args(kwargs):