diff --git a/eo/src/eoFunctorStore.cpp b/eo/src/eoFunctorStore.cpp
index cb8d1a57..43cd778c 100644
--- a/eo/src/eoFunctorStore.cpp
+++ b/eo/src/eoFunctorStore.cpp
@@ -3,6 +3,8 @@
 #pragma warning(disable:4786)
 #endif
 
+#include <cstddef>
+
 #include <eoFunctorStore.h>
 #include <eoFunctor.h>
 
@@ -10,7 +12,7 @@
 /// clears the memory
 eoFunctorStore::~eoFunctorStore()
 {
-    for(size_t i = 0; i < vec.size(); ++i) {
+    for( std::size_t i = 0; i < vec.size(); ++i) {
         delete vec[i];
     }
 }