diff --git a/src/crt/crt0.S b/src/crt/crt0.S
index 12b4c7ce1..3a7112997 100644
--- a/src/crt/crt0.S
+++ b/src/crt/crt0.S
@@ -37,6 +37,7 @@
 	.equ	ti.PopRealO1, 0x0205DC
 	.equ	ti.MovFrOP1, 0x02032C
 	.equ	ti.ClrLCDFull, 0x020808
+	.equ	ti.boot.memclear, 0x0000B0
 
 	.section	.header,"ax",@progbits
 
@@ -173,24 +174,15 @@ ___libload_libs_ret:
 	call	ti.usb_DisableTimer
 	di
 
-.L.bss_zeroize:
-	ld	hl, ___bss_len
-	ld	bc, 0
-	xor	a, a
-	sbc	hl, bc
-	jr	z, .L.bss_done
-	ld	de, ___bss_low
-	push	de
-	ld	(de), a
-	dec	hl
-	sbc	hl, bc
-	pop	hl
-	jr	z, .L.bss_done
+	; zeroize bss
+	ld	hl, ___bss_low
 	ld	bc, ___bss_len
-	dec	bc
-	inc	de
-	ldir
-.L.bss_done:
+	push	bc
+	push	hl
+	; void memclear(void *dst, size_t size)
+	call	ti.boot.memclear
+	pop	hl
+	pop	hl
 
 	res	1, (iy + 0x0D)			; no text buffer
 	res	3, (iy + 0x4A)			; use first shadow buffer