diff --git a/include/PoolObjectSQL.h b/include/PoolObjectSQL.h
index 753ed56063..254aa59a88 100644
--- a/include/PoolObjectSQL.h
+++ b/include/PoolObjectSQL.h
@@ -75,10 +75,10 @@ public:
      */
     enum LockStates
     {
-        ST_NONE      = 0x0LL,
-        ST_USE       = 0x1LL,
-        ST_MANAGE    = 0x2LL,
-        ST_ADMIN     = 0x4LL
+        ST_NONE      = 0,
+        ST_USE       = 1,
+        ST_MANAGE    = 2,
+        ST_ADMIN     = 3
     };
 
     static const long int LockableObject;
@@ -530,7 +530,10 @@ public:
      *
      * @return 0 if the lock was granted, -1 if the object is already locked
      */
-    int lock_db(const int owner, const int req_id, const int level);
+    int lock_db(const int owner,
+                const int req_id,
+                const int level,
+                const bool is_admin);
 
     /**
      * Unlocks the DB lock for external applications. The object must be locked
diff --git a/include/RequestManagerLock.h b/include/RequestManagerLock.h
index d2b4fc5a88..8ea5f31143 100644
--- a/include/RequestManagerLock.h
+++ b/include/RequestManagerLock.h
@@ -40,9 +40,13 @@ protected:
     void request_execute(xmlrpc_c::paramList const& _paramList,
                          RequestAttributes& att) override;
 
-    int lock_db(PoolObjectSQL * object, const int owner, const int req_id, const int level)
+    int lock_db(PoolObjectSQL * object,
+                const int owner,
+                const int req_id,
+                const int level,
+                const bool is_admin)
     {
-        return object->lock_db(owner, req_id, level);
+        return object->lock_db(owner, req_id, level, is_admin);
     };
 };
 
diff --git a/src/acl/AclManager.cc b/src/acl/AclManager.cc
index 2669219a55..e4cd62e178 100644
--- a/src/acl/AclManager.cc
+++ b/src/acl/AclManager.cc
@@ -195,11 +195,11 @@ bool AclManager::authorize(
     long long user_req;
     long long resource_oid_req;
 
-    if (static_cast<long long int>(op) & 0x10LL) //No lockable object
+    if (op & 0x10LL) //No lockable object
     {
         op = static_cast<AuthRequest::Operation>(op & 0x0FLL);
     }
-    else if (obj_perms.locked > 0 && obj_perms.locked <= static_cast<long long int>(op))
+    else if (obj_perms.locked > 0 && obj_perms.locked <= op)
     {
         return false;
     }
@@ -385,11 +385,11 @@ bool AclManager::oneadmin_authorize(
         const PoolObjectAuth&   obj_perms,
         AuthRequest::Operation  op) const
 {
-    if (static_cast<long long int>(op) & 0x10LL) //No lockable object
+    if (op & 0x10LL) //No lockable object
     {
         return true;
     }
-    else if (obj_perms.locked > 0 && obj_perms.locked <= static_cast<long long int>(op))
+    else if (obj_perms.locked > 0 && obj_perms.locked <= op)
     {
         return false;
     }
diff --git a/src/image/Image.cc b/src/image/Image.cc
index 55b9638011..0fdab80fd4 100644
--- a/src/image/Image.cc
+++ b/src/image/Image.cc
@@ -1016,7 +1016,7 @@ void Image::set_state(ImageState _state)
     }
     else if (state == LOCKED)
     {
-        lock_db(-1,-1, PoolObjectSQL::LockStates::ST_USE);
+        lock_db(-1,-1, PoolObjectSQL::LockStates::ST_USE, true);
     }
 
     if (_state != LOCKED )
diff --git a/src/pool/PoolObjectSQL.cc b/src/pool/PoolObjectSQL.cc
index a7331be7d7..78c46da2a3 100644
--- a/src/pool/PoolObjectSQL.cc
+++ b/src/pool/PoolObjectSQL.cc
@@ -587,13 +587,22 @@ bool PoolObjectSQL::name_is_valid(const string& obj_name,
 /* -------------------------------------------------------------------------- */
 /* -------------------------------------------------------------------------- */
 
-int PoolObjectSQL::lock_db(const int owner, const int req_id, const int level)
+int PoolObjectSQL::lock_db(const int owner,
+                           const int req_id,
+                           const int level,
+                           const bool is_admin)
 {
     if ( level < ST_NONE || level > ST_ADMIN )
     {
         return -1;
     }
 
+    if (locked != ST_NONE && lock_owner != owner && !is_admin)
+    {
+        // Only admin can override lock
+        return -1;
+    }
+
     locked      = static_cast<LockStates>(level);
     lock_time   = time(0);
     lock_owner  = owner;
diff --git a/src/rm/RequestManagerLock.cc b/src/rm/RequestManagerLock.cc
index 083aa585b4..8f57774e0b 100644
--- a/src/rm/RequestManagerLock.cc
+++ b/src/rm/RequestManagerLock.cc
@@ -62,6 +62,27 @@ void RequestManagerLock::request_execute(xmlrpc_c::paramList const& paramList,
         return;
     }
 
+    switch(level)
+    {
+        case 1: //USE + MANAGE + ADMIN
+            level = PoolObjectSQL::ST_USE;
+            break;
+        case 2: //MANAGE + ADMIN
+            level = PoolObjectSQL::ST_MANAGE;
+            break;
+        case 3: //ADMIN
+            level = PoolObjectSQL::ST_ADMIN;
+            break;
+        case 4: //ALL equals USE
+            level = PoolObjectSQL::ST_USE;
+            break;
+
+        default:
+            att.resp_msg = "Wrong lock level specified";
+            failure_response(ACTION, att);
+            return;
+    }
+
     if ((auth_object & PoolObjectSQL::LockableObject) != 0)
     {
         if ( test && object->test_lock_db(att.resp_msg) != 0 )
@@ -70,7 +91,7 @@ void RequestManagerLock::request_execute(xmlrpc_c::paramList const& paramList,
         }
         else
         {
-            rc = lock_db(object.get(), owner, att.req_id, level);
+            rc = lock_db(object.get(), owner, att.req_id, level, att.is_admin());
 
             pool->update(object.get());
 
@@ -87,6 +108,7 @@ void RequestManagerLock::request_execute(xmlrpc_c::paramList const& paramList,
     }
     else
     {
+        att.resp_msg = "Object cannot be locked.";
         failure_response(AUTHORIZATION, att);
     }