diff --git a/src/server/slavefuncs.c b/src/server/slavefuncs.c
--- a/src/server/slavefuncs.c
+++ b/src/server/slavefuncs.c
@@ -36,7 +36,7 @@
 /** Converts an integer to a string, currently a stub. */
 char *int_to_str(int nbr)
 {
- return;
+ return(NULL);
 }
 
 /** Generates a SSH key with ssh-keygen */