diff --git a/kaleid/kernel/io/vga.c b/kaleid/kernel/io/vga.c
index 367f2b4..1c6a752 100644
--- a/kaleid/kernel/io/vga.c
+++ b/kaleid/kernel/io/vga.c
@@ -79,9 +79,11 @@ error_t bvgaflusher(Buffer_t *buf)
 
 void IoScrollDown(void)
 {
+    BLockBuf(BStdOut);
     if (bscroll > 0)
         bscroll--;
     bvgaflusher(BStdOut);
+    BUnlockBuf(BStdOut);
 }