diff --git a/src/shell_manager.cc b/src/shell_manager.cc
index d11dc88b2..cfc364cd1 100644
--- a/src/shell_manager.cc
+++ b/src/shell_manager.cc
@@ -11,6 +11,7 @@
 #include <sys/types.h>
 #include <sys/wait.h>
 #include <unistd.h>
+#include <stdlib.h>
 
 extern char **environ;