diff --git a/libc/src/string/memory_utils/memcpy_utils.h b/libc/src/string/memory_utils/memcpy_utils.h
--- a/libc/src/string/memory_utils/memcpy_utils.h
+++ b/libc/src/string/memory_utils/memcpy_utils.h
@@ -34,7 +34,8 @@
 #if defined(LLVM_LIBC_MEMCPY_MONITOR)
   LLVM_LIBC_MEMCPY_MONITOR(dst, src, kBlockSize);
 #elif defined(USE_BUILTIN_MEMCPY_INLINE)
-  __builtin_memcpy_inline(dst, src, kBlockSize);
+  constexpr size_t size = kBlockSize;
+  __builtin_memcpy_inline(dst, src, size);
 #elif defined(USE_BUILTIN_MEMCPY)
   __builtin_memcpy(dst, src, kBlockSize);
 #else