diff --git a/src/win32_window.c b/src/win32_window.c
index 2b04ac71..8788719d 100644
--- a/src/win32_window.c
+++ b/src/win32_window.c
@@ -516,7 +516,7 @@ static LRESULT CALLBACK windowProc(HWND hWnd, UINT uMsg,
         case WM_KEYDOWN:
         case WM_SYSKEYDOWN:
         {
-            const int scancode = (lParam >> 16) & 0xff;
+            const int scancode = (lParam >> 16) & 0x1ff;
             const int key = translateKey(wParam, lParam);
             if (key == _GLFW_KEY_INVALID)
                 break;
@@ -551,7 +551,7 @@ static LRESULT CALLBACK windowProc(HWND hWnd, UINT uMsg,
         case WM_SYSKEYUP:
         {
             const int mods = getKeyMods();
-            const int scancode = (lParam >> 16) & 0xff;
+            const int scancode = (lParam >> 16) & 0x1ff;
             const int key = translateKey(wParam, lParam);
             if (key == _GLFW_KEY_INVALID)
                 break;