diff --git a/extensions/guacamole-auth-mysql/src/main/java/net/sourceforge/guacamole/net/auth/mysql/MySQLConnection.java b/extensions/guacamole-auth-mysql/src/main/java/net/sourceforge/guacamole/net/auth/mysql/MySQLConnection.java
index d0b95f073..a4950d2fc 100644
--- a/extensions/guacamole-auth-mysql/src/main/java/net/sourceforge/guacamole/net/auth/mysql/MySQLConnection.java
+++ b/extensions/guacamole-auth-mysql/src/main/java/net/sourceforge/guacamole/net/auth/mysql/MySQLConnection.java
@@ -108,7 +108,7 @@ public class MySQLConnection extends AbstractConnection {
         if (parentID != null)
             this.setParentIdentifier(String.valueOf(parentID));
         else
-            this.setParentIdentifier(null);
+            this.setParentIdentifier(MySQLConstants.CONNECTION_GROUP_ROOT_IDENTIFIER);
 
     }
 
diff --git a/extensions/guacamole-auth-mysql/src/main/java/net/sourceforge/guacamole/net/auth/mysql/MySQLConnectionGroup.java b/extensions/guacamole-auth-mysql/src/main/java/net/sourceforge/guacamole/net/auth/mysql/MySQLConnectionGroup.java
index cc879f818..f41e6d7e5 100644
--- a/extensions/guacamole-auth-mysql/src/main/java/net/sourceforge/guacamole/net/auth/mysql/MySQLConnectionGroup.java
+++ b/extensions/guacamole-auth-mysql/src/main/java/net/sourceforge/guacamole/net/auth/mysql/MySQLConnectionGroup.java
@@ -129,7 +129,7 @@ public class MySQLConnectionGroup extends AbstractConnectionGroup {
         if (parentID != null)
             this.setParentIdentifier(String.valueOf(parentID));
         else
-            this.setParentIdentifier(null);
+            this.setParentIdentifier(MySQLConstants.CONNECTION_GROUP_ROOT_IDENTIFIER);
 
     }