diff --git a/type/__unbound/files/unbound.conf.sh b/type/__unbound/files/unbound.conf.sh
index 2f7ecff..39443d8 100755
--- a/type/__unbound/files/unbound.conf.sh
+++ b/type/__unbound/files/unbound.conf.sh
@@ -1,5 +1,10 @@
 #!/bin/sh
 
+module_config="validator iterator"
+if [ -n "$DNS64_PREFIX" ]; then
+	module_config="dns64 $module_config"
+fi
+
 generate_interface() {
   for i in $INTERFACES; do
     echo "	interface: $i"
@@ -26,6 +31,12 @@ generate_local_data() {
 	done
 }
 
+generate_dns64_prefix() {
+	if [ -n "$DNS64_PREFIX" ]; then
+		echo "	dns64-prefix: $DNS64_PREFIX"
+	fi
+}
+
 cat << EOF
 #
 # THIS FILE HAS BEEN GENERATED BY CDIST, DO NOT EDIT BY HAND.
@@ -506,7 +517,7 @@ $(generate_access_control)
 	# most modules have to be listed at the beginning of the line,
 	# except cachedb(just before iterator), and python (at the beginning,
 	# or, just before the iterator).
-	module-config: "dns64 validator iterator"
+	module-config: "$module_config"
 
 	# File with trusted keys, kept uptodate using RFC5011 probes,
 	# initial file like trust-anchor-file, then it stores metadata.
@@ -776,7 +787,8 @@ $(generate_local_data)
 
 	# DNS64 prefix. Must be specified when DNS64 is use.
 	# Enable dns64 in module-config.  Used to synthesize IPv6 from IPv4.
-	dns64-prefix: $DNS64_PREFIX
+	# dns64-prefix: $DNS64_PREFIX"
+	$(generate_dns64_prefix)
 
 	# DNS64 ignore AAAA records for these domains and use A instead.
 	# dns64-ignore-aaaa: "example.com"
diff --git a/type/__unbound/man.rst b/type/__unbound/man.rst
index 316d011..05fce45 100644
--- a/type/__unbound/man.rst
+++ b/type/__unbound/man.rst
@@ -13,9 +13,6 @@ answers from specified upstrean DNS server. This is a singleton type.
 
 REQUIRED PARAMETERS
 -------------------
-dns64_prefix
-  IPv6 prefix used for DNS64.
-
 forward_addr
   DNS servers used to lookup names, can be provided multiple times. It can be
   either an IPv4 or IPv6 address but no domain name.
@@ -38,6 +35,9 @@ local_data
   Configure local data, which is served in reply to queries for it. Can be
   specified multiple times.
 
+dns64_prefix
+  Enable DNS64 with specified prefix.
+
 BOOLEAN PARAMETERS
 ------------------
 disable-ip4
diff --git a/type/__unbound/manifest b/type/__unbound/manifest
index 5d6b50f..53a8ab6 100755
--- a/type/__unbound/manifest
+++ b/type/__unbound/manifest
@@ -33,12 +33,15 @@ case "$os" in
 esac
 
 # Required parameters:
-DNS64_PREFIX=$(cat "$__object/parameter/dns64_prefix")
-export DNS64_PREFIX
 FORWARD_ADDRS=$(cat "$__object/parameter/forward_addr")
 export FORWARD_ADDRS
 
 # Optional parameters:
+if [ -f "$__object/parameter/dns64_prefix" ]; then
+	DNS64_PREFIX=$(cat "$__object/parameter/dns64_prefix")
+	export DNS64_PREFIX
+fi
+
 if [ -f "$__object/parameter/interface" ]; then
    INTERFACES=$(cat "$__object/parameter/interface")
    export INTERFACES
diff --git a/type/__unbound/parameter/required b/type/__unbound/parameter/required
deleted file mode 100644
index 4ad232f..0000000
--- a/type/__unbound/parameter/required
+++ /dev/null
@@ -1 +0,0 @@
-dns64_prefix