diff --git a/ansible_mitogen/runner.py b/ansible_mitogen/runner.py
index 16a7d777..d5c2fd2b 100644
--- a/ansible_mitogen/runner.py
+++ b/ansible_mitogen/runner.py
@@ -61,6 +61,15 @@ ansible.module_utils.basic._ANSIBLE_ARGS = '{}'
 LOG = logging.getLogger(__name__)
 
 
+def utf8(s):
+    """
+    Coerce an object to bytes if it is Unicode.
+    """
+    if isinstance(s, unicode):
+        s = s.encode('utf-8')
+    return s
+
+
 def reopen_readonly(fp):
     """
     Replace the file descriptor belonging to the file object `fp` with one
@@ -329,9 +338,9 @@ class ScriptRunner(ProgramRunner):
         if not self.interpreter:
             return s
 
-        shebang = '#!' + self.interpreter
+        shebang = '#!' + utf8(self.interpreter)
         if self.interpreter_arg:
-            shebang += ' ' + self.interpreter_arg
+            shebang += ' ' + utf8(self.interpreter_arg)
 
         new = [shebang]
         if os.path.basename(self.interpreter).startswith('python'):
diff --git a/tests/ansible/integration/runner/all.yml b/tests/ansible/integration/runner/all.yml
index b65b1a53..c3d95005 100644
--- a/tests/ansible/integration/runner/all.yml
+++ b/tests/ansible/integration/runner/all.yml
@@ -9,5 +9,6 @@
 - import_playbook: custom_python_json_args_module.yml
 - import_playbook: custom_python_new_style_module.yml
 - import_playbook: custom_python_want_json_module.yml
+- import_playbook: custom_script_interpreter.yml
 - import_playbook: forking_behaviour.yml
 - import_playbook: remote_tmp.yml
diff --git a/tests/ansible/integration/runner/custom_script_interpreter.yml b/tests/ansible/integration/runner/custom_script_interpreter.yml
new file mode 100644
index 00000000..9ad350bb
--- /dev/null
+++ b/tests/ansible/integration/runner/custom_script_interpreter.yml
@@ -0,0 +1,18 @@
+- name: integration/runner/custom_script_interpreter.yml
+  hosts: all
+  any_errors_fatal: true
+  tasks:
+
+    - custom_bash_old_style_module:
+        foo: true
+      with_sequence: start=1 end={{end|default(1)}}
+      register: out
+      vars:
+        ansible_bash_interpreter: /bin/bash
+
+    - assert:
+        that: |
+          (not out.changed) and
+          (not out.results[0].changed) and
+          out.results[0].msg == 'Here is my input'
+
diff --git a/tests/ansible/lib/modules/custom_bash_old_style_module.sh b/tests/ansible/lib/modules/custom_bash_old_style_module.sh
index 144789cb..9f80dc28 100755
--- a/tests/ansible/lib/modules/custom_bash_old_style_module.sh
+++ b/tests/ansible/lib/modules/custom_bash_old_style_module.sh
@@ -1,6 +1,10 @@
 #!/bin/bash
 # I am an Ansible old-style module.
 
+# This line is to encourage a UnicodeDecodeError in
+# integration/runner/custom_script_interpreter.yml
+#   see https://github.com/dw/mitogen/issues/195
+#   £££ 
 INPUT=$1
 
 [ ! -r "$INPUT" ] && {