diff --git a/src/SMESH/SMESH_Block.cxx b/src/SMESH/SMESH_Block.cxx
index 6a50ff019..59d48a978 100644
--- a/src/SMESH/SMESH_Block.cxx
+++ b/src/SMESH/SMESH_Block.cxx
@@ -21,6 +21,8 @@
 // Created   : Mon Aug  2 10:30:00 2004
 // Author    : Edward AGAPOV (eap)
 
+using namespace std;
+
 #include "SMESH_Block.hxx"
 
 #include <BRepAdaptor_Curve.hxx>
diff --git a/src/SMESH/SMESH_OctreeNode.hxx b/src/SMESH/SMESH_OctreeNode.hxx
index 4feb86842..70133845d 100644
--- a/src/SMESH/SMESH_OctreeNode.hxx
+++ b/src/SMESH/SMESH_OctreeNode.hxx
@@ -27,6 +27,8 @@
 // Author    : Nicolas Geimer & Aurélien Motteux  (OCC)
 // Module    : SMESH
 
+using namespace std;
+
 #ifndef _SMESH_OCTREENODE_HXX_
 #define _SMESH_OCTREENODE_HXX_
 
diff --git a/src/SMESH/SMESH_Pattern.cxx b/src/SMESH/SMESH_Pattern.cxx
index 4d3fe36f6..1ab83c71e 100644
--- a/src/SMESH/SMESH_Pattern.cxx
+++ b/src/SMESH/SMESH_Pattern.cxx
@@ -21,6 +21,8 @@
 // Created   : Mon Aug  2 10:30:00 2004
 // Author    : Edward AGAPOV (eap)
 
+using namespace std;
+
 #include "SMESH_Pattern.hxx"
 
 #include <BRepAdaptor_Curve.hxx>