diff --git a/include/openssl/des.h b/include/openssl/des.h
index aa92c7b..25a7468 100644
--- a/include/openssl/des.h
+++ b/include/openssl/des.h
@@ -144,6 +144,10 @@
 
 /* Deprecated functions. */
 
+/* DES_set_key_unchecked calls |DES_set_key|. */
+OPENSSL_EXPORT void DES_set_key_unchecked(const DES_cblock *key,
+                                          DES_key_schedule *schedule);
+
 OPENSSL_EXPORT void DES_ede3_cfb64_encrypt(const uint8_t *in, uint8_t *out,
                                            long length, DES_key_schedule *ks1,
                                            DES_key_schedule *ks2,