diff --git a/lib/iolog/hostcheck.c b/lib/iolog/hostcheck.c
index 1542cd938..c95a2cb72 100644
--- a/lib/iolog/hostcheck.c
+++ b/lib/iolog/hostcheck.c
@@ -24,6 +24,7 @@
 #if defined(HAVE_OPENSSL)
 # include <sys/socket.h>
 # include <arpa/inet.h>
+# include <stdlib.h>
 # include <string.h>
 # include <netdb.h>