diff --git a/library/x509_crt.c b/library/x509_crt.c
index 1173cae..e6c840c 100644
--- a/library/x509_crt.c
+++ b/library/x509_crt.c
@@ -1391,6 +1391,8 @@
 #if defined(POLARSSL_X509_CRL_PARSE_C)
         /* Check trusted CA's CRL for the chain's top crt */
         *flags |= x509_crt_verifycrl( child, trust_ca, ca_crl );
+#else
+        ((void) ca_crl);
 #endif
 
         if( x509_time_expired( &trust_ca->valid_to ) )