diff --git a/libc-top-half/musl/src/thread/pthread_create.c b/libc-top-half/musl/src/thread/pthread_create.c
index 450fe15a..067104a4 100644
--- a/libc-top-half/musl/src/thread/pthread_create.c
+++ b/libc-top-half/musl/src/thread/pthread_create.c
@@ -458,6 +458,9 @@ int __pthread_create(pthread_t *restrict res, const pthread_attr_t *restrict att
 		if (!map) goto fail;
 #endif
 		tsd = map + size - __pthread_tsd_size;
+#ifndef __wasilibc_unmodified_upstream
+	        memset(tsd, 0, __pthread_tsd_size);
+#endif
 		if (!stack) {
 #ifdef __wasilibc_unmodified_upstream
 			stack = tsd - libc.tls_size;