diff --git a/14.0/unit/Dockerfile b/14.0/unit/Dockerfile
index fbac7cf..7a407b7 100644
--- a/14.0/unit/Dockerfile
+++ b/14.0/unit/Dockerfile
@@ -203,14 +203,14 @@ ENV LDAP_BACKUP_PORT=389
 ENV LDAP_DN=
 ENV LDAP_AGENT_PASSWORD=
 ENV LDAP_BASE=
-ENV LDAP_BASE_USERS
-ENV LDAP_BASE_GROUPS
+ENV LDAP_BASE_USERS=
+ENV LDAP_BASE_GROUPS=
 # space-separated objectclass values
 ENV LDAP_USERFILTER_OBJECTCLASS=inetOrgPerson
-ENV LDAP_USERLIST_FILTER
-ENV LDAP_LOGIN_FILTER
+ENV LDAP_USERLIST_FILTER=
+ENV LDAP_LOGIN_FILTER=
 ENV LDAP_GROUPFILTER_OBJECTCLASS=organizationalRole
-ENV LDAP_GROUP_FILTER
+ENV LDAP_GROUP_FILTER=
 ENV LDAP_GID_NUMBER=gidNumber
 ENV LDAP_DISPLAY_NAME=cn
 ENV LDAP_USER_DISPLAY_NAME_2=
diff --git a/15.0/unit/Dockerfile b/15.0/unit/Dockerfile
index 6bcae4f..bb31b32 100644
--- a/15.0/unit/Dockerfile
+++ b/15.0/unit/Dockerfile
@@ -203,14 +203,14 @@ ENV LDAP_BACKUP_PORT=389
 ENV LDAP_DN=
 ENV LDAP_AGENT_PASSWORD=
 ENV LDAP_BASE=
-ENV LDAP_BASE_USERS
-ENV LDAP_BASE_GROUPS
+ENV LDAP_BASE_USERS=
+ENV LDAP_BASE_GROUPS=
 # space-separated objectclass values
 ENV LDAP_USERFILTER_OBJECTCLASS=inetOrgPerson
-ENV LDAP_USERLIST_FILTER
-ENV LDAP_LOGIN_FILTER
+ENV LDAP_USERLIST_FILTER=
+ENV LDAP_LOGIN_FILTER=
 ENV LDAP_GROUPFILTER_OBJECTCLASS=organizationalRole
-ENV LDAP_GROUP_FILTER
+ENV LDAP_GROUP_FILTER=
 ENV LDAP_GID_NUMBER=gidNumber
 ENV LDAP_DISPLAY_NAME=cn
 ENV LDAP_USER_DISPLAY_NAME_2=
diff --git a/16.0/unit/Dockerfile b/16.0/unit/Dockerfile
index 48e9c8e..78cf1a3 100644
--- a/16.0/unit/Dockerfile
+++ b/16.0/unit/Dockerfile
@@ -203,14 +203,14 @@ ENV LDAP_BACKUP_PORT=389
 ENV LDAP_DN=
 ENV LDAP_AGENT_PASSWORD=
 ENV LDAP_BASE=
-ENV LDAP_BASE_USERS
-ENV LDAP_BASE_GROUPS
+ENV LDAP_BASE_USERS=
+ENV LDAP_BASE_GROUPS=
 # space-separated objectclass values
 ENV LDAP_USERFILTER_OBJECTCLASS=inetOrgPerson
-ENV LDAP_USERLIST_FILTER
-ENV LDAP_LOGIN_FILTER
+ENV LDAP_USERLIST_FILTER=
+ENV LDAP_LOGIN_FILTER=
 ENV LDAP_GROUPFILTER_OBJECTCLASS=organizationalRole
-ENV LDAP_GROUP_FILTER
+ENV LDAP_GROUP_FILTER=
 ENV LDAP_GID_NUMBER=gidNumber
 ENV LDAP_DISPLAY_NAME=cn
 ENV LDAP_USER_DISPLAY_NAME_2=
diff --git a/17.0/unit/Dockerfile b/17.0/unit/Dockerfile
index 12b7659..34715a2 100644
--- a/17.0/unit/Dockerfile
+++ b/17.0/unit/Dockerfile
@@ -203,14 +203,14 @@ ENV LDAP_BACKUP_PORT=389
 ENV LDAP_DN=
 ENV LDAP_AGENT_PASSWORD=
 ENV LDAP_BASE=
-ENV LDAP_BASE_USERS
-ENV LDAP_BASE_GROUPS
+ENV LDAP_BASE_USERS=
+ENV LDAP_BASE_GROUPS=
 # space-separated objectclass values
 ENV LDAP_USERFILTER_OBJECTCLASS=inetOrgPerson
-ENV LDAP_USERLIST_FILTER
-ENV LDAP_LOGIN_FILTER
+ENV LDAP_USERLIST_FILTER=
+ENV LDAP_LOGIN_FILTER=
 ENV LDAP_GROUPFILTER_OBJECTCLASS=organizationalRole
-ENV LDAP_GROUP_FILTER
+ENV LDAP_GROUP_FILTER=
 ENV LDAP_GID_NUMBER=gidNumber
 ENV LDAP_DISPLAY_NAME=cn
 ENV LDAP_USER_DISPLAY_NAME_2=
diff --git a/Dockerfile-unit.template b/Dockerfile-unit.template
index 4055e7c..659ed98 100644
--- a/Dockerfile-unit.template
+++ b/Dockerfile-unit.template
@@ -202,14 +202,14 @@ ENV LDAP_BACKUP_PORT=389
 ENV LDAP_DN=
 ENV LDAP_AGENT_PASSWORD=
 ENV LDAP_BASE=
-ENV LDAP_BASE_USERS
-ENV LDAP_BASE_GROUPS
+ENV LDAP_BASE_USERS=
+ENV LDAP_BASE_GROUPS=
 # space-separated objectclass values
 ENV LDAP_USERFILTER_OBJECTCLASS=inetOrgPerson
-ENV LDAP_USERLIST_FILTER
-ENV LDAP_LOGIN_FILTER
+ENV LDAP_USERLIST_FILTER=
+ENV LDAP_LOGIN_FILTER=
 ENV LDAP_GROUPFILTER_OBJECTCLASS=organizationalRole
-ENV LDAP_GROUP_FILTER
+ENV LDAP_GROUP_FILTER=
 ENV LDAP_GID_NUMBER=gidNumber
 ENV LDAP_DISPLAY_NAME=cn
 ENV LDAP_USER_DISPLAY_NAME_2=