diff --git a/libc/arch-arm/bionic/vfork.S b/libc/arch-arm/bionic/vfork.S
index 8329111..0b17d64 100644
--- a/libc/arch-arm/bionic/vfork.S
+++ b/libc/arch-arm/bionic/vfork.S
@@ -27,12 +27,13 @@
  */
 
 #include <private/bionic_asm.h>
+#include <private/bionic_asm_tls.h>
 
 ENTRY(vfork)
 __BIONIC_WEAK_ASM_FOR_NATIVE_BRIDGE(vfork)
     // __get_tls()[TLS_SLOT_THREAD_ID]->cached_pid_ = 0
     mrc     p15, 0, r3, c13, c0, 3
-    ldr     r3, [r3, #4]
+    ldr     r3, [r3, #(TLS_SLOT_THREAD_ID * 4)]
     mov     r0, #0
     str     r0, [r3, #12]
 
diff --git a/libc/arch-arm64/bionic/vfork.S b/libc/arch-arm64/bionic/vfork.S
index 0a83cc7..6acd64b 100644
--- a/libc/arch-arm64/bionic/vfork.S
+++ b/libc/arch-arm64/bionic/vfork.S
@@ -27,6 +27,7 @@
  */
 
 #include <private/bionic_asm.h>
+#include <private/bionic_asm_tls.h>
 #include <asm/signal.h>
 #include <linux/sched.h>
 
@@ -34,7 +35,7 @@
 __BIONIC_WEAK_ASM_FOR_NATIVE_BRIDGE(vfork)
     // __get_tls()[TLS_SLOT_THREAD_ID]->cached_pid_ = 0
     mrs     x0, tpidr_el0
-    ldr     x0, [x0, #8]
+    ldr     x0, [x0, #(TLS_SLOT_THREAD_ID * 8)]
     str     wzr, [x0, #20]
 
     mov     x0, #(CLONE_VM | CLONE_VFORK | SIGCHLD)
diff --git a/libc/arch-x86/bionic/vfork.S b/libc/arch-x86/bionic/vfork.S
index 79d7899..24ede3d 100644
--- a/libc/arch-x86/bionic/vfork.S
+++ b/libc/arch-x86/bionic/vfork.S
@@ -27,6 +27,7 @@
  */
 
 #include <private/bionic_asm.h>
+#include <private/bionic_asm_tls.h>
 
 // This custom code preserves the return address across the system call.
 
@@ -38,7 +39,7 @@
 
   // __get_tls()[TLS_SLOT_THREAD_ID]->cached_pid_ = 0
   movl    %gs:0, %eax
-  movl    4(%eax), %eax
+  movl    (TLS_SLOT_THREAD_ID * 4)(%eax), %eax
   movl    $0, 12(%eax)
 
   movl    $__NR_vfork, %eax
diff --git a/libc/arch-x86_64/bionic/vfork.S b/libc/arch-x86_64/bionic/vfork.S
index ce96a8c..e32b517 100644
--- a/libc/arch-x86_64/bionic/vfork.S
+++ b/libc/arch-x86_64/bionic/vfork.S
@@ -27,6 +27,7 @@
  */
 
 #include <private/bionic_asm.h>
+#include <private/bionic_asm_tls.h>
 
 // This custom code preserves the return address across the system call.
 
@@ -36,7 +37,7 @@
 
   // __get_tls()[TLS_SLOT_THREAD_ID]->cached_pid_ = 0
   mov    %fs:0, %rax
-  mov    8(%rax), %rax
+  mov    (TLS_SLOT_THREAD_ID * 8)(%rax), %rax
   movl   $0, 20(%rax)
 
   movl    $__NR_vfork, %eax