diff --git a/eo/tutorial/ParadisEO/Lesson2/MasterDistEvalBitEA.cpp b/eo/tutorial/ParadisEO/Lesson2/MasterDistEvalBitEA.cpp
index b2b154ff..0d61b501 100644
--- a/eo/tutorial/ParadisEO/Lesson2/MasterDistEvalBitEA.cpp
+++ b/eo/tutorial/ParadisEO/Lesson2/MasterDistEvalBitEA.cpp
@@ -9,6 +9,8 @@ typedef eoBit<double> Indi ;	// A bitstring with fitness double
 
 #include "binary_value.h"
 
+using namespace std;
+
 void main_function(int argc, char **argv) {
 
   // Some parameters
diff --git a/eo/tutorial/ParadisEO/Lesson2/SlaveDistEvalBitEA.cpp b/eo/tutorial/ParadisEO/Lesson2/SlaveDistEvalBitEA.cpp
index 5194d789..c6cd8969 100644
--- a/eo/tutorial/ParadisEO/Lesson2/SlaveDistEvalBitEA.cpp
+++ b/eo/tutorial/ParadisEO/Lesson2/SlaveDistEvalBitEA.cpp
@@ -9,6 +9,8 @@ typedef eoBit<double> Indi;	// A bitstring with fitness double
 
 #include "binary_value.h"
 
+using namespace std;
+
 void main_function(int argc, char **argv) {
   
   eoEvalFuncPtr <Indi, double, const vector <bool> & > eval (binary_value) ;
diff --git a/eo/tutorial/ParadisEO/Lesson2/binary_value.h b/eo/tutorial/ParadisEO/Lesson2/binary_value.h
index a31c0864..f2f5d6ca 100644
--- a/eo/tutorial/ParadisEO/Lesson2/binary_value.h
+++ b/eo/tutorial/ParadisEO/Lesson2/binary_value.h
@@ -7,7 +7,7 @@
     @param _chrom A binary chromosome 
 */
 // INIT
-double binary_value(const vector<bool>& _chrom)
+double binary_value(const std::vector<bool>& _chrom)
 {
   double sum = 0;
   for (unsigned i = 0; i < _chrom.size(); i++)