diff --git a/eo/src/eoFlight.h b/eo/src/eoFlight.h
index 9af813a2..4c46d8e9 100644
--- a/eo/src/eoFlight.h
+++ b/eo/src/eoFlight.h
@@ -46,7 +46,7 @@ public:
     {
         for (unsigned i = 0; i < _pop.size (); i++)
         {
-            operator  ()(_pop[i]);
+            this->operator  ()(_pop[i]);
         }
 
     }
diff --git a/eo/src/eoParticleBestInit.h b/eo/src/eoParticleBestInit.h
index 050fbc9c..b203c824 100644
--- a/eo/src/eoParticleBestInit.h
+++ b/eo/src/eoParticleBestInit.h
@@ -46,7 +46,7 @@ public:
     {
         for (unsigned i = 0; i < _pop.size (); i++)
         {
-            operator  ()(_pop[i]);
+            this->operator  ()(_pop[i]);
         }
 
     }
diff --git a/eo/src/eoSelectFromWorth.h b/eo/src/eoSelectFromWorth.h
index a2fd5ed2..342be9da 100644
--- a/eo/src/eoSelectFromWorth.h
+++ b/eo/src/eoSelectFromWorth.h
@@ -217,7 +217,7 @@ public:
 
 #ifndef NDEBUG
   // check whether the stuff is still in sync
-  check_sync(index, _pop[index]);
+  this->check_sync(index, _pop[index]);
 #endif
 
     return _pop[index];
diff --git a/eo/src/eoVelocity.h b/eo/src/eoVelocity.h
index 5bbdb7c5..e388078c 100644
--- a/eo/src/eoVelocity.h
+++ b/eo/src/eoVelocity.h
@@ -49,7 +49,7 @@ public:
     {
         for (unsigned i = 0; i < _pop.size (); i++)
         {
-            operator  ()(_pop[i],i);
+            this->operator  ()(_pop[i],i);
         }
 
     }