diff --git a/libc/bionic/libc_init_static.cpp b/libc/bionic/libc_init_static.cpp
index d7a2856..a3c66d4 100644
--- a/libc/bionic/libc_init_static.cpp
+++ b/libc/bionic/libc_init_static.cpp
@@ -356,7 +356,7 @@
       if (memtag_stack) {
         void* pg_start =
             reinterpret_cast<void*>(page_start(reinterpret_cast<uintptr_t>(stack_top)));
-        if (mprotect(pg_start, PAGE_SIZE, PROT_READ | PROT_WRITE | PROT_MTE | PROT_GROWSDOWN)) {
+        if (mprotect(pg_start, page_size(), PROT_READ | PROT_WRITE | PROT_MTE | PROT_GROWSDOWN)) {
           async_safe_fatal("error: failed to set PROT_MTE on main thread stack: %m");
         }
       }