diff --git a/src/kernel/paging.asm b/src/kernel/paging.asm
index b863d59..2d5dd6e 100644
--- a/src/kernel/paging.asm
+++ b/src/kernel/paging.asm
@@ -29,7 +29,7 @@ section .text
 ;referenced in paging.c
 extern invlpg
 invlpg:
-  invlpg byte [rdi]
+  invlpg [rdi]
   ret
 
 extern switch_to_kernel_page_tables
diff --git a/src/kernel/serial.asm b/src/kernel/serial.asm
index c9ddc1e..a4731dc 100644
--- a/src/kernel/serial.asm
+++ b/src/kernel/serial.asm
@@ -52,7 +52,7 @@ global write_serial_string_n
 write_serial_string_n:
   test esi, esi
   jz .ret
-  movzx rcx, esi
+  mov ecx, esi
 
 .wait_ready:
   mov dx, 0x03fd