diff --git a/reactos/subsystems/win32/win32k/ntuser/msgqueue.c b/reactos/subsystems/win32/win32k/ntuser/msgqueue.c
index 35ed255edaa..f7aa35318db 100644
--- a/reactos/subsystems/win32/win32k/ntuser/msgqueue.c
+++ b/reactos/subsystems/win32/win32k/ntuser/msgqueue.c
@@ -616,7 +616,8 @@ co_MsqInsertMouseMessage(MSG* Msg, DWORD flags, ULONG_PTR dwExtraInfo, BOOL Hook
    MouseHistoryOfMoves[gcur_count].y = Msg->pt.y;
    MouseHistoryOfMoves[gcur_count].time = Msg->time;
    MouseHistoryOfMoves[gcur_count].dwExtraInfo = dwExtraInfo;
-   if (gcur_count++ == 64) gcur_count = 0; // 0 - 63 is 64, FIFO forwards.
+   if (++gcur_count == ARRAYSIZE(MouseHistoryOfMoves))
+      gcur_count = 0; // 0 - 63 is 64, FIFO forwards.
 }
 
 //