diff --git a/c_tools/mock/loaders/simulation_loader.cpp b/c_tools/mock/loaders/simulation_loader.cpp
index 80e09b2..70c441a 100644
--- a/c_tools/mock/loaders/simulation_loader.cpp
+++ b/c_tools/mock/loaders/simulation_loader.cpp
@@ -95,6 +95,9 @@ void SimulationLoader::basicPreprocessing(SimuData *d,
     }
   filteredCopy(d->Id, accepted, d->NumPart);
   filteredCopy(d->type, accepted, d->NumPart);
+  
+  filterAttribute<long>(d, "uniqueID", accepted, d->NumPart);
+  
   d->NumPart = numAccepted;
   delete[] accepted;
 }
diff --git a/c_tools/mock/loaders/simulation_loader.hpp b/c_tools/mock/loaders/simulation_loader.hpp
index 8805702..149ee10 100644
--- a/c_tools/mock/loaders/simulation_loader.hpp
+++ b/c_tools/mock/loaders/simulation_loader.hpp
@@ -110,17 +110,27 @@ public:
 
     while (i < N)
       {
-	if (!accepted[i])
-	  {
-	    i++;
-	    continue;
-	  }
+        if (!accepted[i])
+          {
+            i++;
+            continue;
+          }
 
-	a[j] = a[i];
-	j++;
-	i++;
+        a[j] = a[i];
+        j++;
+        i++;
       }
   }
+  
+  template<typename T>
+  void filterAttribute(CosmoTool::SimuData *d, const std::string& attrname, bool *accepted, long NumPart)
+  {
+    if (d->attributes.find(attrname) == d->attributes.end())
+      return;
+ 
+    long *l = d->as<T>(attrname);
+    filteredCopy<T>(l, accepted, NumPart);
+  }
 };