diff --git a/implot_demo.cpp b/implot_demo.cpp
index 55baebb..05f5add 100644
--- a/implot_demo.cpp
+++ b/implot_demo.cpp
@@ -29,6 +29,7 @@
 #include <implot.h>
 #include <math.h>
 #include <stdio.h>
+#include <stdlib.h>
 
 namespace {