diff --git a/crypto/compat/crypto_lock_win.c b/crypto/compat/crypto_lock_win.c
index 47c3dcc..ef21eee 100644
--- a/crypto/compat/crypto_lock_win.c
+++ b/crypto/compat/crypto_lock_win.c
@@ -17,6 +17,8 @@
 
 #include <windows.h>
 
+#include <openssl/crypto.h>
+
 static HANDLE locks[CRYPTO_NUM_LOCKS];
 
 void