diff --git a/libc/private/bionic_macros.h b/libc/private/bionic_macros.h
index 4800e3a..13934e5 100644
--- a/libc/private/bionic_macros.h
+++ b/libc/private/bionic_macros.h
@@ -87,3 +87,12 @@
 #else
 #define __BIONIC_FALLTHROUGH
 #endif
+
+template <typename T>
+static inline T* untag_address(T* p) {
+#if defined(__aarch64__)
+  return reinterpret_cast<T*>(reinterpret_cast<uintptr_t>(p) & ((1ULL << 56) - 1));
+#else
+  return p;
+#endif
+}