diff --git a/reactos/dll/win32/kernel32/file/deviceio.c b/reactos/dll/win32/kernel32/file/deviceio.c
index 670002d36aa..fa00d7051c3 100644
--- a/reactos/dll/win32/kernel32/file/deviceio.c
+++ b/reactos/dll/win32/kernel32/file/deviceio.c
@@ -132,6 +132,10 @@ DeviceIoControl(IN HANDLE hDevice,
              /* lpBytesReturned must not be NULL here, in fact Win doesn't
                 check that case either and crashes (only after the operation
                 completed) */
+            if (!lpBytesReturned)
+            {
+                ERR("Bad caller: lpBytesReturned must not be NULL");
+            }
              *lpBytesReturned = Iosb.Information;
           }
         else
@@ -184,6 +188,10 @@ GetOverlappedResult (
     }
   }
 
+  if (!lpNumberOfBytesTransferred)
+  {
+      ERR("Bad caller: lpNumberOfBytesTransferred must not be NULL");
+  }
   *lpNumberOfBytesTransferred = lpOverlapped->InternalHigh;
 
   if (!NT_SUCCESS(lpOverlapped->Internal))