diff --git a/cube/User/Src/counter.c b/cube/User/Src/counter.c
index 4da9a8d..5198703 100644
--- a/cube/User/Src/counter.c
+++ b/cube/User/Src/counter.c
@@ -1,5 +1,6 @@
 #include <stdint.h>
 #include <string.h>
+#include <stdlib.>
 
 #include <tim.h>