diff --git a/Modules/_hacl/Lib_Memzero0.c b/Modules/_hacl/Lib_Memzero0.c
index 5b1a2f7797db76..5c269d231de82f 100644
--- a/Modules/_hacl/Lib_Memzero0.c
+++ b/Modules/_hacl/Lib_Memzero0.c
@@ -36,7 +36,7 @@ void Lib_Memzero0_memzero0(void *dst, uint64_t len) {
   size_t len_ = (size_t) len;
 
   #ifdef _WIN32
-    SecureZeroMemory(dst, len);
+    SecureZeroMemory(dst, len_);
   #elif defined(__APPLE__) && defined(__MACH__)
     memset_s(dst, len_, 0, len_);
   #elif (defined(__linux__) && !defined(LINUX_NO_EXPLICIT_BZERO)) || defined(__FreeBSD__)