diff --git a/reactos/ntoskrnl/io/iomgr/device.c b/reactos/ntoskrnl/io/iomgr/device.c
index 97643b680f8..f5f6dd6284b 100644
--- a/reactos/ntoskrnl/io/iomgr/device.c
+++ b/reactos/ntoskrnl/io/iomgr/device.c
@@ -486,7 +486,7 @@ IopDereferenceDeviceObject(IN PDEVICE_OBJECT DeviceObject,
     ASSERT(DeviceObject->ReferenceCount);
 
     /* Dereference the device */
-    DeviceObject->ReferenceCount--;
+    InterlockedDecrement(&DeviceObject->ReferenceCount);
 
     /*
      * Check if we can unload it and it's safe to unload (or if we're forcing
diff --git a/reactos/ntoskrnl/io/iomgr/file.c b/reactos/ntoskrnl/io/iomgr/file.c
index 4898352bdad..6dacf5c833e 100644
--- a/reactos/ntoskrnl/io/iomgr/file.c
+++ b/reactos/ntoskrnl/io/iomgr/file.c
@@ -157,7 +157,7 @@ IopCheckDeviceAndDriver(IN POPEN_PACKET OpenPacket,
     else
     {
         /* Increase reference count */
-        DeviceObject->ReferenceCount++;
+        InterlockedIncrement(&DeviceObject->ReferenceCount);
         return STATUS_SUCCESS;
     }
 }