diff --git a/src/server/gdb_server.c b/src/server/gdb_server.c
index 002b5873b..00c04e363 100644
--- a/src/server/gdb_server.c
+++ b/src/server/gdb_server.c
@@ -3315,7 +3315,7 @@ static int gdb_input_inner(struct connection *connection)
 					/* '?' is sent after the eventual '!' */
 					if (!warn_use_ext && !gdb_con->extended_protocol) {
 						warn_use_ext = true;
-						LOG_WARNING("Prefer GDB command \"target extended-remote %s\" instead of \"target remote %s\"",
+						LOG_WARNING("Prefer GDB command \"target extended-remote :%s\" instead of \"target remote :%s\"",
 									connection->service->port, connection->service->port);
 					}
 					break;