diff --git a/demo/demo/map.cpp b/demo/demo/map.cpp
index b380c5d..e12fc36 100644
--- a/demo/demo/map.cpp
+++ b/demo/demo/map.cpp
@@ -28,9 +28,9 @@ void convertFilename(std::string &filename,const std::string l_folder, const std
 int main(int argc, char *argv[]) 
 {
     char ntype = 'y';
-    char *config_filename = "../demo/config.yaml";
-    char * net = "yolo3.rt";
-    char * labels_path = "../demo/COCO_val2017/all_labels.txt";
+    const char *config_filename = "../demo/config.yaml";
+    const char * net = "yolo3.rt";
+    const char * labels_path = "../demo/COCO_val2017/all_labels.txt";
     bool show = false;
     bool write_dets = false;
     bool write_res_on_file = true;
diff --git a/include/tkDNN/evaluation.h b/include/tkDNN/evaluation.h
index b8d68d5..d76bb7d 100644
--- a/include/tkDNN/evaluation.h
+++ b/include/tkDNN/evaluation.h
@@ -31,7 +31,7 @@ struct PR
     void print();
 };
 
-void readmAPParams( char* config_filename, int& classes, int& map_points, 
+void readmAPParams( const char* config_filename, int& classes, int& map_points, 
                     int& map_levels, float& map_step, float& IoU_thresh, 
                     float& conf_thresh, bool& verbose);
 
diff --git a/src/evaluation.cpp b/src/evaluation.cpp
index cc0118f..62f9e9b 100644
--- a/src/evaluation.cpp
+++ b/src/evaluation.cpp
@@ -16,7 +16,7 @@ void PR::print(){
     std::cout<<"precision: "<<precision<<" recall: "<<recall<<" tp: "<<tp<<" fp:"<<fp<<" fn:"<<fn<<std::endl;
 }
 
-void readmAPParams( char* config_filename, int& classes, int& map_points, 
+void readmAPParams( const char* config_filename, int& classes, int& map_points, 
                     int& map_levels, float& map_step, float& IoU_thresh, 
                     float& conf_thresh, bool& verbose) {
     YAML::Node config   = YAML::LoadFile(config_filename);