diff --git a/expected/wasm32-wasi/posix/defined-symbols.txt b/expected/wasm32-wasi/posix/defined-symbols.txt
index d1544592b..d92bcbd88 100644
--- a/expected/wasm32-wasi/posix/defined-symbols.txt
+++ b/expected/wasm32-wasi/posix/defined-symbols.txt
@@ -90,6 +90,7 @@ __getopt_msg
 __gmtime_r
 __hwcap
 __inet_aton
+__init_tp
 __intscan
 __invtrigl_R
 __isalnum_l
@@ -324,6 +325,7 @@ __wasi_fd_seek
 __wasi_fd_sync
 __wasi_fd_tell
 __wasi_fd_write
+__wasi_init_tp
 __wasi_path_create_directory
 __wasi_path_filestat_get
 __wasi_path_filestat_set_times
diff --git a/expected/wasm32-wasi/single/defined-symbols.txt b/expected/wasm32-wasi/single/defined-symbols.txt
index f8f445707..23ff87197 100644
--- a/expected/wasm32-wasi/single/defined-symbols.txt
+++ b/expected/wasm32-wasi/single/defined-symbols.txt
@@ -275,6 +275,7 @@ __wasi_fd_seek
 __wasi_fd_sync
 __wasi_fd_tell
 __wasi_fd_write
+__wasi_init_tp
 __wasi_path_create_directory
 __wasi_path_filestat_get
 __wasi_path_filestat_set_times
diff --git a/libc-bottom-half/crt/crt1-command.c b/libc-bottom-half/crt/crt1-command.c
index 6e2bcd942..3bcad84ba 100644
--- a/libc-bottom-half/crt/crt1-command.c
+++ b/libc-bottom-half/crt/crt1-command.c
@@ -1,3 +1,4 @@
+#include "libc.h"
 #include <wasi/api.h>
 extern void __wasm_call_ctors(void);
 extern int __main_void(void);
@@ -7,6 +8,11 @@ extern void __wasm_call_dtors(void);
 // that the `_start` function isn't started more than once.
 static volatile int started = 0;
 
+static void dummy_0()
+{
+}
+weak_alias(dummy_0, __wasi_init_tp);
+
 __attribute__((export_name("_start")))
 void _start(void) {
     // Don't allow the program to be called multiple times.
@@ -15,6 +21,8 @@ void _start(void) {
     }
     started = 1;
 
+	__wasi_init_tp();
+
     // The linker synthesizes this to call constructors.
     __wasm_call_ctors();
 
diff --git a/libc-top-half/musl/src/env/__init_tls.c b/libc-top-half/musl/src/env/__init_tls.c
index bd041b2c7..ee785bc11 100644
--- a/libc-top-half/musl/src/env/__init_tls.c
+++ b/libc-top-half/musl/src/env/__init_tls.c
@@ -15,16 +15,23 @@
 
 volatile int __thread_list_lock;
 
-#ifdef __wasilibc_unmodified_upstream
+#ifndef __wasilibc_unmodified_upstream
+void __wasi_init_tp() {
+	__init_tp((void *)__get_tp());
+}
+#endif
+
 int __init_tp(void *p)
 {
 	pthread_t td = p;
 	td->self = td;
+#ifdef __wasilibc_unmodified_upstream
 	int r = __set_thread_area(TP_ADJ(p));
 	if (r < 0) return -1;
 	if (!r) libc.can_do_threads = 1;
 	td->detach_state = DT_JOINABLE;
 	td->tid = __syscall(SYS_set_tid_address, &__thread_list_lock);
+#endif
 	td->locale = &libc.global_locale;
 	td->robust_list.head = &td->robust_list.head;
 	td->sysinfo = __sysinfo;
@@ -32,6 +39,8 @@ int __init_tp(void *p)
 	return 0;
 }
 
+#ifdef __wasilibc_unmodified_upstream
+
 static struct builtin_tls {
 	char c;
 	struct pthread pt;