diff --git a/crypto/threads_lib.c b/crypto/threads_lib.c
index 0c7162392d..240ef726ec 100644
--- a/crypto/threads_lib.c
+++ b/crypto/threads_lib.c
@@ -8,7 +8,8 @@
  */
 #include <openssl/crypto.h>
 
-#ifndef OPENSSL_NO_DEPRECATED_3_0
+#ifdef OPENSSL_SYS_UNIX
+# ifndef OPENSSL_NO_DEPRECATED_3_0
 
 void OPENSSL_fork_prepare(void)
 {
@@ -22,4 +23,5 @@ void OPENSSL_fork_child(void)
 {
 }
 
+# endif
 #endif