diff --git a/kernel/arch/i386/Thread.S b/kernel/arch/i386/Thread.S
index 30e8811e..d0b6a04f 100644
--- a/kernel/arch/i386/Thread.S
+++ b/kernel/arch/i386/Thread.S
@@ -4,44 +4,17 @@ read_ip:
 	popl %eax
 	jmp *%eax
 
-exit_thread_trampoline:
-	addl $4, %esp
-	pushl (%esp)
-	ret
-
 # void start_thread(uint32_t sp, uint32_t ip)
 .global start_thread
 start_thread:
-	movl 8(%esp), %ecx
-	movl 4(%esp), %esp
-	movl $0, %ebp
-	pushl $exit_thread_trampoline
-	sti
-	jmp *%ecx
+	ud2
 
 # void continue_thread(uint32_t sp, uint32_t ip)
 .global continue_thread
 continue_thread:
-	movl 8(%esp), %ecx
-	movl 4(%esp), %esp
-	movl $0, %eax
-	jmp *%ecx
+	ud2
 
-# void thread_jump_userspace(uint32_t sp, uint32_t ip)
-.global thread_jump_userspace
-thread_jump_userspace:
-	movl $0x23, %eax
-	movw %ax, %ds
-	movw %ax, %es
-	movw %ax, %fs
-	movw %ax, %gs
-
-	movl 8(%esp), %ecx
-	movl 4(%esp), %esp
-
-	pushl $0x23
-	pushl %esp
-	pushfl
-	pushl $0x1B
-	pushl %ecx
-	iret
+# void thread_userspace_trampoline(uint32_t sp, uint32_t ip, int argc, char** argv, char** envp)
+.global thread_userspace_trampoline
+thread_userspace_trampoline:
+	ud2
diff --git a/kernel/arch/x86_64/Thread.S b/kernel/arch/x86_64/Thread.S
index 62973ada..de1e59ab 100644
--- a/kernel/arch/x86_64/Thread.S
+++ b/kernel/arch/x86_64/Thread.S
@@ -1,4 +1,4 @@
-# uint64_t read_()
+# uint64_t read_ip()
 .global read_ip
 read_ip:
 	popq %rax