diff --git a/src/sort_demo.cpp b/src/sort_demo.cpp
index 758faee4..3f50f7bd 100644
--- a/src/sort_demo.cpp
+++ b/src/sort_demo.cpp
@@ -1,5 +1,5 @@
 
-
+#include <cstdlib>
 #include <iostream>
 #include "sort.h"
 
@@ -114,4 +114,4 @@ int main (int argc, char const *argv[])
 	
 	
 	return 0;
-}
\ No newline at end of file
+}