diff --git a/include/laser/processor/processor_closeloop_icp.h b/include/laser/processor/processor_closeloop_icp.h
index e06f241b84df4f398924c3f40c3e34202932f2c3..9b78bd18dd2c51206deeb61582451f5a31ee4e8f 100644
--- a/include/laser/processor/processor_closeloop_icp.h
+++ b/include/laser/processor/processor_closeloop_icp.h
@@ -26,7 +26,7 @@ struct ProcessorParamsCloseLoopICP : public ProcessorParamsBase
     {
         match_past_key_frame = _server.getParam<int>(_unique_name + "/match_past_key_frame");
     }
-    std::string print()
+    std::string print() const
     {
         return "\n" + ProcessorParamsBase::print()
             + "match_past_key_frame: " + std::to_string(match_past_key_frame) + "\n";
diff --git a/include/laser/processor/processor_odom_icp.h b/include/laser/processor/processor_odom_icp.h
index 221160f8fe2f3a9543f5d7eac75ed5a9186f3deb..138687cc2ac81d37d9516ba4f178fb1a3fcf38d7 100644
--- a/include/laser/processor/processor_odom_icp.h
+++ b/include/laser/processor/processor_odom_icp.h
@@ -50,7 +50,7 @@ struct ProcessorParamsOdomICP : public ProcessorParamsTracker
         vfk_min_error              = _server.getParam<double>   (_unique_name   + "/vfk_min_error");
         vfk_max_points             = _server.getParam<int>      (_unique_name   + "/vfk_max_points");
     }
-    std::string print() {
+    std::string print() const {
         return "\n" + ProcessorParamsTracker::print() + "\n"
                 + "use_point_to_line_distance: "+ std::to_string(use_point_to_line_distance)+ "\n"
                 + "max_correspondence_dist: "   + std::to_string(max_correspondence_dist)   + "\n"
diff --git a/include/laser/processor/processor_tracker_feature_polyline_2D.h b/include/laser/processor/processor_tracker_feature_polyline_2D.h
index f50d33fd87074be6dd234990a63ba2cc50787a33..d6804f771e9c78b718194cf78c417b442c39041a 100644
--- a/include/laser/processor/processor_tracker_feature_polyline_2D.h
+++ b/include/laser/processor/processor_tracker_feature_polyline_2D.h
@@ -44,7 +44,7 @@ struct ProcessorParamsTrackerFeaturePolyline2D : public ProcessorParamsTrackerFe
         {
             // TODO write parser!
         }
-        std::string print()
+        std::string print() const
         {
             return "\n" + ProcessorParamsTrackerFeature::print();
             // TODO write printer!
diff --git a/include/laser/sensor/sensor_laser_2D.h b/include/laser/sensor/sensor_laser_2D.h
index 3fd5c68f30c0896c4e25ae9f3e11ffa0d553ff91..88528cd1a36b7e2f9de96f311aac457981e45dd7 100644
--- a/include/laser/sensor/sensor_laser_2D.h
+++ b/include/laser/sensor/sensor_laser_2D.h
@@ -34,7 +34,7 @@ struct IntrinsicsLaser2D : public IntrinsicsBase
             scan_params.range_std_dev_  = _server.getParam<double>(_unique_name + "/LaserScanParams/range_std_dev");
             scan_params.angle_std_dev_  = _server.getParam<double>(_unique_name + "/LaserScanParams/angle_std_dev");
         }
-        std::string print()
+        std::string print() const
         {
             return "\n" + IntrinsicsBase::print()                                                   + "\n"
             + "LaserScanParams/angle_min: "         + std::to_string(scan_params.angle_min_)        + "\n"