diff --git a/ansible_mitogen/planner.py b/ansible_mitogen/planner.py
index 254b203d..7e3aa39a 100644
--- a/ansible_mitogen/planner.py
+++ b/ansible_mitogen/planner.py
@@ -208,28 +208,26 @@ class ScriptPlanner(BinaryPlanner):
     Common functionality for script module planners -- handle interpreter
     detection and rewrite.
     """
-    def _rewrite_interpreter(self, invocation, interpreter):
-        key = u'ansible_%s_interpreter' % os.path.basename(interpreter).strip()
-        try:
-            template = invocation.task_vars[key].strip()
-            return invocation.templar.template(template)
-        except KeyError:
-            return interpreter
-
-    def plan(self, invocation, **kwargs):
+    def _get_interpreter(self, invocation):
         interpreter, arg = parse_script_interpreter(invocation.module_source)
         if interpreter is None:
             raise ansible.errors.AnsibleError(NO_INTERPRETER_MSG % (
                 invocation.module_name,
             ))
 
+        key = u'ansible_%s_interpreter' % os.path.basename(interpreter).strip()
+        try:
+            template = invocation.task_vars[key].strip()
+            return invocation.templar.template(template), arg
+        except KeyError:
+            return interpreter, arg
+
+    def plan(self, invocation, **kwargs):
+        interpreter, arg = self._get_interpreter(invocation)
         return super(ScriptPlanner, self).plan(
             invocation=invocation,
             interpreter_arg=arg,
-            interpreter=self._rewrite_interpreter(
-                interpreter=interpreter,
-                invocation=invocation
-            ),
+            interpreter=interpreter,
             **kwargs
         )
 
@@ -301,6 +299,9 @@ class NewStylePlanner(ScriptPlanner):
     """
     runner_name = 'NewStyleRunner'
 
+    def _get_interpreter(self, invocation):
+        return None, None
+
     def get_should_fork(self, invocation):
         """
         In addition to asynchronous tasks, new-style modules should be forked
diff --git a/tests/ansible/integration/runner/all.yml b/tests/ansible/integration/runner/all.yml
index c3d95005..9ede6984 100644
--- a/tests/ansible/integration/runner/all.yml
+++ b/tests/ansible/integration/runner/all.yml
@@ -7,6 +7,7 @@
 - import_playbook: custom_perl_json_args_module.yml
 - import_playbook: custom_perl_want_json_module.yml
 - import_playbook: custom_python_json_args_module.yml
+- import_playbook: custom_python_new_style_missing_interpreter.yml
 - import_playbook: custom_python_new_style_module.yml
 - import_playbook: custom_python_want_json_module.yml
 - import_playbook: custom_script_interpreter.yml
diff --git a/tests/ansible/integration/runner/custom_python_new_style_missing_interpreter.yml b/tests/ansible/integration/runner/custom_python_new_style_missing_interpreter.yml
new file mode 100644
index 00000000..6ffc90d5
--- /dev/null
+++ b/tests/ansible/integration/runner/custom_python_new_style_missing_interpreter.yml
@@ -0,0 +1,17 @@
+
+- name: integration/runner__custom_python_new_style_module.yml
+  hosts: all
+  any_errors_fatal: true
+  tasks:
+    - custom_python_new_style_missing_interpreter:
+        foo: true
+      with_sequence: start=1 end={{end|default(1)}}
+      register: out
+
+    - assert:
+        that: |
+          (not out.changed) and
+          (not out.results[0].changed) and
+          out.results[0].input[0].ANSIBLE_MODULE_ARGS.foo and
+          out.results[0].msg == 'Here is my input'
+
diff --git a/tests/ansible/lib/modules/custom_python_new_style_missing_interpreter.py b/tests/ansible/lib/modules/custom_python_new_style_missing_interpreter.py
new file mode 100644
index 00000000..4d1bb23f
--- /dev/null
+++ b/tests/ansible/lib/modules/custom_python_new_style_missing_interpreter.py
@@ -0,0 +1,26 @@
+# I am an Ansible new-style Python module, but I lack an interpreter.
+
+import json
+import sys
+
+# This is the magic marker Ansible looks for:
+# from ansible.module_utils.
+
+
+def usage():
+    sys.stderr.write('Usage: %s <input.json>\n' % (sys.argv[0],))
+    sys.exit(1)
+
+# Also must slurp in our own source code, to verify the encoding string was
+# added.
+with open(sys.argv[0]) as fp:
+    me = fp.read()
+
+input_json = sys.stdin.read()
+
+print "{"
+print "  \"changed\": false,"
+print "  \"msg\": \"Here is my input\","
+print "  \"source\": [%s]," % (json.dumps(me),)
+print "  \"input\": [%s]" % (input_json,)
+print "}"