diff --git a/kernel_entry.S b/kernel_entry.S
index 9cd45d9..be22530 100644
--- a/kernel_entry.S
+++ b/kernel_entry.S
@@ -35,6 +35,13 @@ stack_top:
 _start:
     movl $stack_top, %esp
 
+    cld
+    movl $__bss_start, %edi
+    movl $__bss_end, %ecx
+    subl %edi, %ecx
+    xorl %eax, %eax
+    rep stosb
+
     movl $pdpt, %eax
     orl $0x03, %eax
     movl %eax, pml4