diff --git a/src/network.c b/src/network.c
index 9caef04..a0c4396 100644
--- a/src/network.c
+++ b/src/network.c
@@ -249,7 +249,7 @@ CLEANUP:
  * Convert the network address into either a dotted-decimal or an IPv6
  * hex string.
  */
-char *get_ip_string (struct sockaddr *sa, char *buf, size_t buflen)
+const char *get_ip_string (struct sockaddr *sa, char *buf, size_t buflen)
 {
         assert (sa != NULL);
         assert (buf != NULL);
diff --git a/src/network.h b/src/network.h
index b6ddaa6..15af481 100644
--- a/src/network.h
+++ b/src/network.h
@@ -27,7 +27,7 @@ extern ssize_t safe_read (int fd, char *buffer, size_t count);
 extern int write_message (int fd, const char *fmt, ...);
 extern ssize_t readline (int fd, char **whole_buffer);
 
-extern char *get_ip_string (struct sockaddr *sa, char *buf, size_t len);
+extern const char *get_ip_string (struct sockaddr *sa, char *buf, size_t len);
 extern int full_inet_pton (const char *ip, void *dst);
 
 #endif