diff --git a/src/shared/io-glib.c b/src/shared/io-glib.c
index 6316037..882ebd6 100644
--- a/src/shared/io-glib.c
+++ b/src/shared/io-glib.c
@@ -25,6 +25,8 @@
 #include <config.h>
 #endif
 
+#include <errno.h>
+
 #include <glib.h>
 
 #include "src/shared/io.h"
@@ -122,7 +124,7 @@ void io_destroy(struct io *io)
 int io_get_fd(struct io *io)
 {
 	if (!io)
-		return -1;
+		return -ENOTCONN;
 
 	return g_io_channel_unix_get_fd(io->channel);
 }
diff --git a/src/shared/io-mainloop.c b/src/shared/io-mainloop.c
index 1563ce5..b7e0f5f 100644
--- a/src/shared/io-mainloop.c
+++ b/src/shared/io-mainloop.c
@@ -26,6 +26,7 @@
 #endif
 
 #include <unistd.h>
+#include <errno.h>
 #include <sys/socket.h>
 
 #include "monitor/mainloop.h"
@@ -192,7 +193,7 @@ void io_destroy(struct io *io)
 int io_get_fd(struct io *io)
 {
 	if (!io)
-		return -1;
+		return -ENOTCONN;
 
 	return io->fd;
 }