diff --git a/lib/dns/include/dns/rpz.h b/lib/dns/include/dns/rpz.h
index 64311550d2..245b0ea47d 100644
--- a/lib/dns/include/dns/rpz.h
+++ b/lib/dns/include/dns/rpz.h
@@ -94,7 +94,7 @@ typedef isc_uint64_t	    dns_rpz_zbits_t;
  * Avoid hassles with (1<<33) or (1<<65)
  */
 #define DNS_RPZ_ZMASK(n)    ((dns_rpz_zbits_t)((((n) >= DNS_RPZ_MAX_ZONES-1) ? \
-						0 : (1<<((n)+1))) -1))
+						0 : (1ULL<<((n)+1))) -1))
 
 /*
  * The trigger counter type.