diff --git a/DMRLookup.cpp b/DMRLookup.cpp
index e9de15b..d358ed7 100644
--- a/DMRLookup.cpp
+++ b/DMRLookup.cpp
@@ -20,6 +20,7 @@
 #include "Log.h"
 
 #include <cstdio>
+#include <cstdlib>
 #include <cstring>
 #include <cctype>