diff --git a/library/psa_crypto.c b/library/psa_crypto.c
index 1de1955..e41e512 100644
--- a/library/psa_crypto.c
+++ b/library/psa_crypto.c
@@ -1065,6 +1065,7 @@
     return( PSA_SUCCESS );
 }
 
+#if defined(MBEDTLS_CMAC_C)
 static int psa_cmac_start( psa_mac_operation_t *operation,
                            size_t key_bits,
                            key_slot_t *slot,
@@ -1085,6 +1086,7 @@
                                       key_bits );
     return( ret );
 }
+#endif /* MBEDTLS_CMAC_C */
 
 static int psa_hmac_start( psa_mac_operation_t *operation,
                            psa_key_type_t key_type,