diff --git a/api/setup/setup.inc.php b/api/setup/setup.inc.php
index 381aa71a75..d8b3079ff2 100644
--- a/api/setup/setup.inc.php
+++ b/api/setup/setup.inc.php
@@ -11,7 +11,7 @@
 /* Basic information about this app */
 $setup_info['api']['name']      = 'api';
 $setup_info['api']['title']     = 'EGroupware API';
-$setup_info['api']['version']   = '17.1.003';
+$setup_info['api']['version']   = '17.1.004';
 $setup_info['api']['versions']['current_header'] = '1.29';
 // maintenance release in sync with changelog in doc/rpm-build/debian.changes
 $setup_info['api']['versions']['maintenance_release'] = '17.1.20180831';
diff --git a/api/setup/tables_update.inc.php b/api/setup/tables_update.inc.php
index eeb7639a89..faceb9a689 100644
--- a/api/setup/tables_update.inc.php
+++ b/api/setup/tables_update.inc.php
@@ -453,3 +453,18 @@ function api_upgrade17_1_002()
 
 	return $GLOBALS['setup_info']['api']['currentver'] = '17.1.003';
 }
+
+/**
+ * Fix forced preferences with value '' (casted to from false) to '0' eg. addressbook:private_addressbook
+ *
+ * Forced preferences with value '' behave unexpected, false values of type "check" need to be written as "0".
+ *
+ * @return type
+ */
+function api_upgrade17_1_003()
+{
+	Api\Preferences::change_preference(null, '/.*/', '0', '', 'forced');
+
+	return $GLOBALS['setup_info']['api']['currentver'] = '17.1.004';
+}
+
diff --git a/setup/inc/class.setup.inc.php b/setup/inc/class.setup.inc.php
index 3ef7d460e4..8a888d45c0 100644
--- a/setup/inc/class.setup.inc.php
+++ b/setup/inc/class.setup.inc.php
@@ -744,11 +744,11 @@ class setup
 		{
 			if (isset($setting['default']))
 			{
-				$default[$name] = (string)$setting['default'];
+				$default[$name] = $setting['default'] === false && $setting['type'] === 'check' ? '0' : (string)$setting['default'];
 			}
 			if (isset($setting['forced']))
 			{
-				$forced[$name] = (string)$setting['forced'];
+				$forced[$name] = $setting['forced'] === false && $setting['type'] === 'check' ? '0' : (string)$setting['forced'];
 			}
 		}
 		// store default/forced preferences, if any found