diff --git a/library/pk_internal.h b/library/pk_internal.h
index ae32955..ece2f82 100644
--- a/library/pk_internal.h
+++ b/library/pk_internal.h
@@ -119,6 +119,16 @@
 #if defined(MBEDTLS_ECP_HAVE_CURVE25519) || defined(MBEDTLS_ECP_HAVE_CURVE448)
 #define MBEDTLS_PK_HAVE_RFC8410_CURVES
 #endif /* MBEDTLS_ECP_HAVE_CURVE25519 || MBEDTLS_ECP_DP_CURVE448 */
+
+#define MBEDTLS_PK_IS_RFC8410_GROUP_ID(id)  \
+    ((id == MBEDTLS_ECP_DP_CURVE25519) || (id == MBEDTLS_ECP_DP_CURVE448))
+
+static inline int mbedtls_pk_is_rfc8410(const mbedtls_pk_context *pk)
+{
+    mbedtls_ecp_group_id id = mbedtls_pk_get_group_id(pk);
+
+    return MBEDTLS_PK_IS_RFC8410_GROUP_ID(id);
+}
 #endif /* MBEDTLS_PK_HAVE_ECC_KEYS */
 
 /* Helper for (deterministic) ECDSA */