diff --git a/tools/roslaunch/src/roslaunch/core.py b/tools/roslaunch/src/roslaunch/core.py
index a6d43e371e..2aedc45432 100644
--- a/tools/roslaunch/src/roslaunch/core.py
+++ b/tools/roslaunch/src/roslaunch/core.py
@@ -208,9 +208,9 @@ def setup_env(node, machine, master_uri, env=None):
         if ns[-1] == '/':
             ns = ns[:-1]
         if ns:
-            d[rosgraph.ROS_NAMESPACE] = ns 
+            d[rosgraph.ROS_NAMESPACE] = str(ns)
         for name, value in node.env_args:
-            d[name] = value
+            d[str(name)] = str(value)
 
     return d