diff --git a/src/_cffi_src/openssl/cryptography.py b/src/_cffi_src/openssl/cryptography.py
index 7cbcb591dd68..a0e22932c261 100644
--- a/src/_cffi_src/openssl/cryptography.py
+++ b/src/_cffi_src/openssl/cryptography.py
@@ -32,7 +32,9 @@
 #include <openssl/e_os2.h>
 #endif
 #if defined(_WIN32)
+#if !defined(WIN32_LEAN_AND_MEAN)
 #define WIN32_LEAN_AND_MEAN
+#endif
 #include <windows.h>
 #include <Wincrypt.h>
 #include <Winsock2.h>
diff --git a/src/rust/build.rs b/src/rust/build.rs
index 9ac388e2b995..5ed7bb0facd6 100644
--- a/src/rust/build.rs
+++ b/src/rust/build.rs
@@ -77,6 +77,10 @@ fn main() {
         // build.define("Py_LIMITED_API", "0x030600f0");
     }
 
+    if cfg!(windows) {
+        build.define("WIN32_LEAN_AND_MEAN", None);
+    }
+
     build.compile("_openssl.a");
 }