diff --git a/doc/guix.texi b/doc/guix.texi
index a79b777826..50487a5172 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -28126,7 +28126,7 @@ The zabbix-server package.
 @item @code{user} (default: @code{"zabbix"}) (type: string)
 User who will run the Zabbix server.
 
-@item @code{group} (default: @code{"zabbix"}) (type: group)
+@item @code{group} (default: @code{"zabbix"}) (type: string)
 Group who will run the Zabbix server.
 
 @item @code{db-host} (default: @code{"127.0.0.1"}) (type: string)
@@ -28212,7 +28212,7 @@ The zabbix-agent package.
 @item @code{user} (default: @code{"zabbix"}) (type: string)
 User who will run the Zabbix agent.
 
-@item @code{group} (default: @code{"zabbix"}) (type: group)
+@item @code{group} (default: @code{"zabbix"}) (type: string)
 Group who will run the Zabbix agent.
 
 @item @code{hostname} (default: @code{""}) (type: string)
diff --git a/gnu/services/monitoring.scm b/gnu/services/monitoring.scm
index d6dc2c1e03..f12b7acb1f 100644
--- a/gnu/services/monitoring.scm
+++ b/gnu/services/monitoring.scm
@@ -224,15 +224,12 @@ Prometheus.")
 
 
 (define (serialize-string field-name val)
-  (if (and (string? val) (string=? val ""))
+  (if (or (eq? 'user field-name)
+          (eq? 'group field-name)
+          (and (string? val) (string=? val "")))
       ""
       (serialize-field field-name val)))
 
-(define group? string?)
-
-(define serialize-group
-  (const ""))
-
 (define include-files? list?)
 
 (define (serialize-include-files field-name val)
@@ -256,8 +253,8 @@ Prometheus.")
   (user
    (string "zabbix")
    "User who will run the Zabbix server.")
-  (group ;for zabbix-server-account procedure
-   (group "zabbix")
+  (group
+   (string "zabbix")
    "Group who will run the Zabbix server.")
   (db-host
    (string "127.0.0.1")
@@ -438,7 +435,7 @@ results in a Web interface.")))
    (string "zabbix")
    "User who will run the Zabbix agent.")
   (group
-   (group "zabbix")
+   (string "zabbix")
    "Group who will run the Zabbix agent.")
   (hostname
    (string "")