diff --git a/core/admin.c b/core/admin.c
index ab1f5afc6df7503d00f671cd8fa5383f113fc165..d521a99158299927167fd2b7a2ddf1cda9b951d8 100644
--- a/core/admin.c
+++ b/core/admin.c
@@ -1457,7 +1457,7 @@ case 107:
 
 	if (p != pe) {
 		start(out);
-		tbuf_append(out, unknown_command, sizeof(unknown_command));
+		tbuf_append(out, unknown_command, sizeof(unknown_command) - 1);
 		end(out);
 	}
 
diff --git a/core/admin.rl b/core/admin.rl
index 1be63602a494048b7bd4b5bf0dfba04b491dcc74..514b467a4f86a13c813b132f1a2455bd9e55dbbe 100644
--- a/core/admin.rl
+++ b/core/admin.rl
@@ -203,7 +203,7 @@ admin_dispatch(void)
 
 	if (p != pe) {
 		start(out);
-		tbuf_append(out, unknown_command, sizeof(unknown_command));
+		tbuf_append(out, unknown_command, sizeof(unknown_command) - 1);
 		end(out);
 	}
 
diff --git a/test/lib/tarantool_admin.py b/test/lib/tarantool_admin.py
index 9e2fffc6b79e4a81509d5b2298a1bd2a9ce69d5e..4788002c2933f24e16659c7fcd279c2b9a1a67d7 100644
--- a/test/lib/tarantool_admin.py
+++ b/test/lib/tarantool_admin.py
@@ -40,11 +40,11 @@ class TarantoolAdmin(TarantoolConnection):
       if not buf:
         break
       res = res + buf;
-      if (res.rfind("...\r\n") >= 0):
+      if (res.rfind("\r\n...\r\n") >= 0):
         break
 
     # validate yaml by parsing it
-    # yaml.load(res)
+    yaml.load(res)
 
     if not noprint:
       print command.replace('\n', '')