diff --git a/converter/converter.cc b/converter/converter.cc
index f065c2b..64643bb 100644
--- a/converter/converter.cc
+++ b/converter/converter.cc
@@ -62,7 +62,7 @@ Converter::Converter(){
 Converter::~Converter(){
 }
 
-std::vector<unsigned int> Converter::newComposition(int type, float posX, float posZ){
+std::vector<int> Converter::newComposition(int type, float posX, float posZ){
     XMLElement* newComposition = doc->NewElement("composition");
     doc->InsertFirstChild(newComposition);
     
@@ -102,7 +102,7 @@ std::vector<unsigned int> Converter::newComposition(int type, float posX, float
     newComposition->InsertFirstChild(xRot);
     newComposition->InsertFirstChild(scale);
     
-    std::vector<unsigned int> ret = nextID;
+    std::vector<int> ret = nextID;
     nextID[1] += 1;
     if (nextID[1] == 255){
         nextID[1] = 0;
@@ -158,7 +158,7 @@ void Converter::save(){
     doc->SaveFile(charXmlFile);
 }
 
-std::vector<unsigned int> Converter::getNextID(){
+std::vector<int> Converter::getNextID(){
     return nextID;
 }
 
diff --git a/converter/converter.hh b/converter/converter.hh
index 3e72b96..7b603f9 100644
--- a/converter/converter.hh
+++ b/converter/converter.hh
@@ -12,14 +12,14 @@ class Converter {
         Converter();
         ~Converter();
         void updateComposition(int idG, int idB, float posX, float posZ); //updates the position of a composition
-        std::vector<unsigned int> newComposition(int type, float posX, float posZ);//creates a new composition and returns its ID
+        std::vector<int> newComposition(int type, float posX, float posZ);//creates a new composition and returns its ID
 	    void deleteComposition(int idG, int idB);
 	    void save();                            //writes the xml to file
-	    std::vector<unsigned int> getNextID();  //returns the next unused ID
+	    std::vector<int> getNextID();  //returns the next unused ID
 
     private:
 
-        std::vector<unsigned int> nextID;
+        std::vector<int> nextID;
         void errorCheck(XMLError error);
         std::string xmlFile;
         XMLDocument* doc = new XMLDocument();
diff --git a/converter/main.cc b/converter/main.cc
index a18f867..81faafc 100644
--- a/converter/main.cc
+++ b/converter/main.cc
@@ -34,7 +34,7 @@ int main( int argc, char *argv[] ){
             //if there is a composition here, adjust the xml and image
             if(image[pixel]!=0 && image[pixel]!=255){
                 if((image[pixel+1]==0 && image[pixel+2]==0) || (image[pixel+1]==255 && image[pixel+2]==255)){
-                    std::vector<unsigned int> temp;
+                    std::vector<int> temp;
                     temp = conv.newComposition(image[pixel], 0.5+rowNum-0.5*height, 0.5+columnNum-0.5*width);
                     idFound[temp[0]][temp[1]] = true;
                     image[pixel+1] = temp[0];