diff --git a/include/mbedtls/asn1.h b/include/mbedtls/asn1.h
index 6b79196..d2162fe 100644
--- a/include/mbedtls/asn1.h
+++ b/include/mbedtls/asn1.h
@@ -578,7 +578,7 @@
  *
  * \return      NULL if not found, or a pointer to the existing entry.
  */
-mbedtls_asn1_named_data *mbedtls_asn1_find_named_data( mbedtls_asn1_named_data *list,
+const mbedtls_asn1_named_data *mbedtls_asn1_find_named_data( const mbedtls_asn1_named_data *list,
                                        const char *oid, size_t len );
 
 /**