diff --git a/ChangeLog.txt b/ChangeLog.txt
index 8e7f05d529..4e8bde1f22 100644
--- a/ChangeLog.txt
+++ b/ChangeLog.txt
@@ -16,6 +16,7 @@ Broker:
   before a role that was attached to the group or client is deleted.
   Closes #1998.
 - Improve logging in dynsec addGroupRole command. Closes #2005.
+- Improve logging in dynsec addGroupClient command. Closes #2008.
 
 Client library:
 - Improve documentation around the `_v5()` and non-v5 functions, e.g.
diff --git a/plugins/dynamic-security/groups.c b/plugins/dynamic-security/groups.c
index a6ede436d4..d66e4dba6e 100644
--- a/plugins/dynamic-security/groups.c
+++ b/plugins/dynamic-security/groups.c
@@ -507,7 +507,7 @@ int dynsec_groups__add_client(const char *username, const char *groupname, int p
 	HASH_FIND(hh, group->clientlist, username, strlen(username), clientlist);
 	if(clientlist != NULL){
 		/* Client is already in the group */
-		return MOSQ_ERR_SUCCESS;
+		return MOSQ_ERR_ALREADY_EXISTS;
 	}
 
 	rc = dynsec_clientlist__add(&group->clientlist, client, priority);
@@ -567,6 +567,8 @@ int dynsec_groups__process_add_client(cJSON *j_responses, struct mosquitto *cont
 		dynsec__command_reply(j_responses, context, "addGroupClient", "Client not found", correlation_data);
 	}else if(rc == ERR_GROUP_NOT_FOUND){
 		dynsec__command_reply(j_responses, context, "addGroupClient", "Group not found", correlation_data);
+	}else if(rc == MOSQ_ERR_ALREADY_EXISTS){
+		dynsec__command_reply(j_responses, context, "addGroupClient", "Client is already in this group", correlation_data);
 	}else{
 		dynsec__command_reply(j_responses, context, "addGroupClient", "Internal error", correlation_data);
 	}
diff --git a/www/posts/2021/01/version-2-0-5-released.md b/www/posts/2021/01/version-2-0-5-released.md
index 23886ce285..3b148dd1c4 100644
--- a/www/posts/2021/01/version-2-0-5-released.md
+++ b/www/posts/2021/01/version-2-0-5-released.md
@@ -26,6 +26,7 @@ Version 2.0.5 of Mosquitto has been released. This is a bugfix release.
   before a role that was attached to the group or client is deleted.
   Closes [#1998].
 - Improve logging in dynsec addGroupRole command. Closes [#2005].
+- Improve logging in dynsec addGroupClient command. Closes [#2008].
 
 # Client library
 - Improve documentation around the `_v5()` and non-v5 functions, e.g.
@@ -52,3 +53,4 @@ Version 2.0.5 of Mosquitto has been released. This is a bugfix release.
 [#1998]: https://github.com/eclipse/mosquitto/issues/1998
 [#1999]: https://github.com/eclipse/mosquitto/issues/1999
 [#2005]: https://github.com/eclipse/mosquitto/issues/2005
+[#2008]: https://github.com/eclipse/mosquitto/issues/2008