diff --git a/arch/x86_64/start_64.S b/arch/x86_64/start_64.S
index 1efbcc4..d0bd140 100644
--- a/arch/x86_64/start_64.S
+++ b/arch/x86_64/start_64.S
@@ -12,11 +12,11 @@ kernel_identifier:
 .section .boot.text, "ax", @progbits
 
 vga_clear:
-	mov $0xb8000, %edi		# VGA buffer
-	mov $0xFA0, %ecx		# 4,000 bytes to clear
-	mov $0x0, %eax
+	mov $0xb8000, %rdi		# VGA buffer
+	mov $500, %rcx			# 4,000 bytes to clear = 500 quadwords
+	mov $0x0, %rax
 
-	rep stosb
+	rep stosq
 
 	ret