diff --git a/Plugin/PluginManager.cpp b/Plugin/PluginManager.cpp
index b599f8e69e037aa50924c42df1fa4bd9db4fe712..f683d6c48b30d1492badf5d3d65601d1dee6481a 100644
--- a/Plugin/PluginManager.cpp
+++ b/Plugin/PluginManager.cpp
@@ -4,6 +4,8 @@
 // bugs and problems to <gmsh@geuz.org>.
 
 #include <map>
+#include <stdlib.h>
+
 #include "GmshConfig.h"
 #include "Plugin.h"
 #include "PluginManager.h"