diff --git a/launch/include/gmapping.launch b/launch/include/gmapping.launch
index 3588c149ef432209a605a2b47efacdf151ecddbb..d367b7290d09513ffb8c7612ca385fe897169d6c 100644
--- a/launch/include/gmapping.launch
+++ b/launch/include/gmapping.launch
@@ -9,8 +9,8 @@
   <arg name="base_frame_id" default="$(arg ns)/base_footprint"/>
   <arg name="config"        default="$(find iri_rosnav)/params/gmapping.yaml"/>
   <arg name="gmapping_scan_topic"    default="$(arg ns)/scan"/>
-  <arg name="map_topic"     default="$(arg ns/map"/>
-  <arg name="output" default="screen" />
+  <arg name="map_topic"     default="/$(arg ns)/map"/>
+  <arg name="output"        default="screen" />
   <arg name="launch_prefix" default="" />
   
   <group ns="$(arg ns)">
@@ -26,7 +26,7 @@
       <param name="map_frame"  value="$(arg map_frame_id)"/>
       <param name="odom_frame" value="$(arg odom_frame_id)"/>
       <param name="base_frame" value="$(arg base_frame_id)"/>
-      <param name="delta"         value="$(arg resolution)"/>
+      <param name="delta"      value="$(arg resolution)"/>
     </node>
     
   </group>