diff --git a/crypto/asn1/a_object.c b/crypto/asn1/a_object.c
index bf386dd..1557435 100644
--- a/crypto/asn1/a_object.c
+++ b/crypto/asn1/a_object.c
@@ -263,7 +263,7 @@
         OPENSSL_free(a);
 }
 
-ASN1_OBJECT *ASN1_OBJECT_create(int nid, unsigned char *data, int len,
+ASN1_OBJECT *ASN1_OBJECT_create(int nid, const unsigned char *data, int len,
                                 const char *sn, const char *ln)
 {
     ASN1_OBJECT o;
diff --git a/include/openssl/asn1.h b/include/openssl/asn1.h
index 5e9aa3f..0347d0d 100644
--- a/include/openssl/asn1.h
+++ b/include/openssl/asn1.h
@@ -883,7 +883,8 @@
 OPENSSL_EXPORT int i2t_ASN1_OBJECT(char *buf, int buf_len,
                                    const ASN1_OBJECT *a);
 
-OPENSSL_EXPORT ASN1_OBJECT *ASN1_OBJECT_create(int nid, unsigned char *data,
+OPENSSL_EXPORT ASN1_OBJECT *ASN1_OBJECT_create(int nid,
+                                               const unsigned char *data,
                                                int len, const char *sn,
                                                const char *ln);