diff --git a/comedi_config/comedi_config.c b/comedi_config/comedi_config.c
index bb23355..c320c14 100644
--- a/comedi_config/comedi_config.c
+++ b/comedi_config/comedi_config.c
@@ -32,6 +32,7 @@
 #include <getopt.h>
 #include <errno.h>
 #include <string.h>
+#include <stdlib.h>
 #include <unistd.h>
 
 #include <comedi.h>