--- a/testing/mozbase/mozrunner/mozrunner/base/runner.py
+++ b/testing/mozbase/mozrunner/mozrunner/base/runner.py
@@ -106,31 +106,32 @@ class BaseRunner(object):
         self.stop()
 
         # attach a debugger, if specified
         if debug_args:
             cmd = list(debug_args) + cmd
 
         if self.logger:
             self.logger.info('Application command: %s' % ' '.join(cmd))
+
+        encoded_env = {}
+        for k in self.env:
+            v = self.env[k]
+            if isinstance(v, unicode_type):
+                v = v.encode('utf-8')
+            if isinstance(k, unicode_type):
+                k = k.encode('utf-8')
+            encoded_env[k] = v
+
         if interactive:
-            filtered_env = {}
-            for k in self.env:
-                v = self.env[k]
-                if isinstance(v, unicode_type):
-                    v = v.encode('utf-8')
-                if isinstance(k, unicode_type):
-                    k = k.encode('utf-8')
-                filtered_env[k] = v
-
-            self.process_handler = subprocess.Popen(cmd, env=filtered_env)
+            self.process_handler = subprocess.Popen(cmd, env=encoded_env)
             # TODO: other arguments
         else:
             # this run uses the managed processhandler
-            self.process_handler = self.process_class(cmd, env=self.env, **self.process_args)
+            self.process_handler = self.process_class(cmd, env=encoded_env, **self.process_args)
             self.process_handler.run(self.timeout, self.output_timeout)
 
         self.crashed = 0
         return self.process_handler.pid
 
     def wait(self, timeout=None):
         """
         Wait for the process to exit.