diff --git a/tools/pymol_asphere/src/error.cpp b/tools/pymol_asphere/src/error.cpp
index 0bbd0905669b8d6724abda9d1610f32822017994..9491ca04a4c23763b143e2833030df03694fe466 100644
--- a/tools/pymol_asphere/src/error.cpp
+++ b/tools/pymol_asphere/src/error.cpp
@@ -13,7 +13,8 @@
 
 #include "error.h"
 #include <cstring>
- 
+#include <cstdlib>
+
 Notice::Notice() {
 	nullout=new ostream(NULL);
 	noteout=&cout;