diff --git a/server-mysql/centos/Dockerfile b/server-mysql/centos/Dockerfile
index 6c263e893..c9aed806e 100644
--- a/server-mysql/centos/Dockerfile
+++ b/server-mysql/centos/Dockerfile
@@ -15,7 +15,7 @@ RUN set -eux && \
     groupadd --system --gid 1995 zabbix && \
     useradd \
             --system --comment "Zabbix monitoring system" \
-            -g zabbix -G root -G dialout \
+            -g zabbix -G root,dialout \
             --uid 1997 \
             --shell /sbin/nologin \
             --home-dir /var/lib/zabbix/ \
diff --git a/server-pgsql/centos/Dockerfile b/server-pgsql/centos/Dockerfile
index 0ad8e6ee0..96ebc6c8f 100644
--- a/server-pgsql/centos/Dockerfile
+++ b/server-pgsql/centos/Dockerfile
@@ -15,7 +15,7 @@ RUN set -eux && \
     groupadd --system --gid 1995 zabbix && \
     useradd \
             --system --comment "Zabbix monitoring system" \
-            -g zabbix -G root -G dialout \
+            -g zabbix -G root,dialout \
             --uid 1997 \
             --shell /sbin/nologin \
             --home-dir /var/lib/zabbix/ \
diff --git a/zabbix-appliance/rhel/Dockerfile b/zabbix-appliance/rhel/Dockerfile
index 5f141ee05..f7ff3cf35 100644
--- a/zabbix-appliance/rhel/Dockerfile
+++ b/zabbix-appliance/rhel/Dockerfile
@@ -85,7 +85,7 @@ RUN INSTALL_PKGS="OpenIPMI-libs \
     groupadd --system --gid 1995 zabbix && \
     useradd \
             --system --comment "Zabbix monitoring system" \
-            -g zabbix -G root -G dialout \
+            -g zabbix -G root,dialout \
             --uid 1997 \
             --shell /sbin/nologin \
             --home-dir /var/lib/zabbix/ \