diff --git a/xtoskrnl/includes/ps/quota.hh b/xtoskrnl/includes/ps/quota.hh
index a97ac62..4129e93 100644
--- a/xtoskrnl/includes/ps/quota.hh
+++ b/xtoskrnl/includes/ps/quota.hh
@@ -19,19 +19,19 @@ namespace PS
     {
         private:
             STATIC EPROCESS_QUOTA_BLOCK DefaultQuotaBlock;
+            STATIC KSPIN_LOCK QuotaLock;
 
         public:
+            STATIC XTFASTCALL VOID ReturnProcessQuota(IN PEPROCESS_QUOTA_BLOCK QuotaBlock,
+                                                      IN PEPROCESS Process,
+                                                      IN PS_QUOTA_TYPE QuotaType,
+                                                      IN SIZE_T Amount);
             STATIC XTAPI VOID ReturnSharedPoolQuota(IN PEPROCESS_QUOTA_BLOCK QuotaBlock,
                                                     IN SIZE_T PagedAmount,
                                                     IN SIZE_T NonPagedAmount);
 
         private:
             STATIC XTAPI VOID DereferenceQuotaBlock(IN PEPROCESS_QUOTA_BLOCK QuotaBlock);
-            STATIC XTFASTCALL VOID ReturnProcessQuota(IN PEPROCESS_QUOTA_BLOCK QuotaBlock,
-                                                      IN PEPROCESS Process,
-                                                      IN PS_QUOTA_TYPE QuotaType,
-                                                      IN SIZE_T Amount);
-
     };
 }
 
diff --git a/xtoskrnl/ps/data.cc b/xtoskrnl/ps/data.cc
index b196cb7..ed2c545 100644
--- a/xtoskrnl/ps/data.cc
+++ b/xtoskrnl/ps/data.cc
@@ -20,3 +20,6 @@ POBJECT_TYPE PS::ProcessManager::ThreadType;
 
 /* Default system-wide quota block assigned to processes */
 EPROCESS_QUOTA_BLOCK PS::Quota::DefaultQuotaBlock;
+
+/* Lock used for quota management */
+KSPIN_LOCK PS::Quota::QuotaLock;