diff --git a/dlls/wldap32/winldap_private.h b/dlls/wldap32/winldap_private.h
index 2902daea974..47a67968651 100644
--- a/dlls/wldap32/winldap_private.h
+++ b/dlls/wldap32/winldap_private.h
@@ -23,6 +23,7 @@
 #include "winternl.h"
 #include "winnls.h"
 
+#define LDAP_NEEDS_PROTOTYPES
 #include <lber.h>
 #include <ldap.h>