diff --git a/tests/debugtalk.py b/tests/debugtalk.py
index 87a7ee8b..74b9a3d3 100644
--- a/tests/debugtalk.py
+++ b/tests/debugtalk.py
@@ -89,8 +89,8 @@ def teardown_hook_sleep_N_secs(response, n_secs):
 def hook_print(msg):
     print(msg)
 
-def modify_headers_os_platform(request, os_platform):
-    request["headers"]["os_platform"] = os_platform
+def modify_request_json(request, os_platform):
+    request["json"]["os_platform"] = os_platform
 
 def setup_hook_httpntlmauth(request):
     if "httpntlmauth" in request:
diff --git a/tests/test_runner.py b/tests/test_runner.py
index 5917205f..38d5f508 100644
--- a/tests/test_runner.py
+++ b/tests/test_runner.py
@@ -164,19 +164,19 @@ class TestRunner(ApiServerUnittest):
                 "method": "POST",
                 "headers": {
                     "content-type": "application/json",
-                    "user_agent": "iOS/10.3",
-                    "os_platform": "ios"
+                    "user_agent": "iOS/10.3"
                 },
                 "json": {
+                    "os_platform": "ios",
                     "sign": "f1219719911caae89ccc301679857ebfda115ca2"
                 }
             },
             "setup_hooks": [
-                "${modify_headers_os_platform($request, android)}"
+                "${modify_request_json($request, android)}"
             ],
             "validate": [
                 {"check": "status_code", "expect": 200},
-                {"check": "content.headers.Os-Platform", "expect": "android"}
+                {"check": "content.json.os_platform", "expect": "android"}
             ]
         }
         test_runner = runner.Runner(config_dict, self.debugtalk_functions)