diff --git a/lib/tests/modules.sh b/lib/tests/modules.sh
index 65de8e378c7e..e0774383720b 100755
--- a/lib/tests/modules.sh
+++ b/lib/tests/modules.sh
@@ -115,6 +115,11 @@ set -- config.enable ./declare-enable.nix ./define-enable.nix ./define-loaOfSub-
 checkConfigError 'The option .* defined in .* does not exist.' "$@"
 checkConfigOutput "true" "$@" ./define-module-check.nix
 
+# Check coerced value.
+checkConfigOutput "\"42\"" config.value ./declare-coerced-value.nix
+checkConfigOutput "\"24\"" config.value ./declare-coerced-value.nix ./define-value-string.nix
+checkConfigError 'The option value .* in .* is not a coercedTo.' config.value ./declare-coerced-value.nix ./define-value-list.nix
+
 cat <<EOF
 ====== module tests ======
 $pass Pass
diff --git a/lib/tests/modules/declare-coerced-value.nix b/lib/tests/modules/declare-coerced-value.nix
new file mode 100644
index 000000000000..76b12ad53f00
--- /dev/null
+++ b/lib/tests/modules/declare-coerced-value.nix
@@ -0,0 +1,10 @@
+{ lib, ... }:
+
+{
+  options = {
+    value = lib.mkOption {
+      default = 42;
+      type = lib.types.coercedTo lib.types.int builtins.toString lib.types.str;
+    };
+  };
+}
diff --git a/lib/tests/modules/define-value-list.nix b/lib/tests/modules/define-value-list.nix
new file mode 100644
index 000000000000..4831c1cc09ba
--- /dev/null
+++ b/lib/tests/modules/define-value-list.nix
@@ -0,0 +1,3 @@
+{
+  value = [];
+}
diff --git a/lib/tests/modules/define-value-string.nix b/lib/tests/modules/define-value-string.nix
new file mode 100644
index 000000000000..e7a166965a7a
--- /dev/null
+++ b/lib/tests/modules/define-value-string.nix
@@ -0,0 +1,3 @@
+{
+  value = "24";
+}
diff --git a/lib/types.nix b/lib/types.nix
index 9366d394da73..0d1a88a00f2d 100644
--- a/lib/types.nix
+++ b/lib/types.nix
@@ -352,6 +352,28 @@ rec {
       functor = (defaultFunctor name) // { wrapped = [ t1 t2 ]; };
     };
 
+    coercedTo = coercedType: coerceFunc: finalType:
+      assert coercedType.getSubModules == null;
+      mkOptionType rec {
+        name = "coercedTo";
+        description = "${finalType.description} or ${coercedType.description}";
+        check = x: finalType.check x || coercedType.check x;
+        merge = loc: defs:
+          let
+            coerceVal = val:
+              if finalType.check val then val
+              else let
+                coerced = coerceFunc val;
+              in assert finalType.check coerced; coerced;
+
+          in finalType.merge loc (map (def: def // { value = coerceVal def.value; }) defs);
+        getSubOptions = finalType.getSubOptions;
+        getSubModules = finalType.getSubModules;
+        substSubModules = m: coercedTo coercedType coerceFunc (finalType.substSubModules m);
+        typeMerge = t1: t2: null;
+        functor = (defaultFunctor name) // { wrapped = finalType; };
+      };
+
     # Obsolete alternative to configOf.  It takes its option
     # declarations from the ‘options’ attribute of containing option
     # declaration.
diff --git a/nixos/doc/manual/configuration/ipv6-config.xml b/nixos/doc/manual/configuration/ipv6-config.xml
index bf86926f9bf5..6d9e0a164e9e 100644
--- a/nixos/doc/manual/configuration/ipv6-config.xml
+++ b/nixos/doc/manual/configuration/ipv6-config.xml
@@ -22,5 +22,25 @@ boot.kernel.sysctl."net.ipv6.conf.eth0.disable_ipv6" = true;
 </programlisting>
 </para>
 
+<para>As with IPv4 networking interfaces are automatically configured via
+DHCPv6. You can configure an interface manually:
+
+<programlisting>
+networking.interfaces.eth0.ip6 = [ { address = "fe00:aa:bb:cc::2"; prefixLength = 64; } ];
+</programlisting>
+</para>
+
+<para>For configuring a gateway, optionally with explicitly specified interface:
+
+<programlisting>
+networking.defaultGateway6 = {
+  address = "fe00::1";
+  interface = "enp0s3";
+}
+</programlisting>
+</para>
+
+<para>See <xref linkend='sec-ipv4' /> for similar examples and additional information.
+</para>
 
 </section>
diff --git a/nixos/modules/tasks/network-interfaces-scripted.nix b/nixos/modules/tasks/network-interfaces-scripted.nix
index c50ea5c79643..aa86fc85feb6 100644
--- a/nixos/modules/tasks/network-interfaces-scripted.nix
+++ b/nixos/modules/tasks/network-interfaces-scripted.nix
@@ -102,17 +102,21 @@ in
                 EOF
 
                 # Set the default gateway.
-                ${optionalString (cfg.defaultGateway != null && cfg.defaultGateway != "") ''
+                ${optionalString (cfg.defaultGateway != null && cfg.defaultGateway.address != "") ''
                   # FIXME: get rid of "|| true" (necessary to make it idempotent).
-                  ip route add default via "${cfg.defaultGateway}" ${
+                  ip route add default via "${cfg.defaultGateway.address}" ${
                     optionalString (cfg.defaultGatewayWindowSize != null)
-                      "window ${toString cfg.defaultGatewayWindowSize}"} || true
+                      "window ${toString cfg.defaultGatewayWindowSize}"} ${
+                    optionalString (cfg.defaultGateway.interface != null)
+                      "dev ${cfg.defaultGateway.interface}"}|| true
                 ''}
-                ${optionalString (cfg.defaultGateway6 != null && cfg.defaultGateway6 != "") ''
+                ${optionalString (cfg.defaultGateway6 != null && cfg.defaultGateway6.address != "") ''
                   # FIXME: get rid of "|| true" (necessary to make it idempotent).
-                  ip -6 route add ::/0 via "${cfg.defaultGateway6}" ${
+                  ip -6 route add ::/0 via "${cfg.defaultGateway6.address}" ${
                     optionalString (cfg.defaultGatewayWindowSize != null)
-                      "window ${toString cfg.defaultGatewayWindowSize}"} || true
+                      "window ${toString cfg.defaultGatewayWindowSize}"} ${
+                    optionalString (cfg.defaultGateway6.interface != null)
+                      "dev ${cfg.defaultGateway6.interface}"} || true
                 ''}
               '';
           };
diff --git a/nixos/modules/tasks/network-interfaces-systemd.nix b/nixos/modules/tasks/network-interfaces-systemd.nix
index 974041d7e1a5..a1212c905560 100644
--- a/nixos/modules/tasks/network-interfaces-systemd.nix
+++ b/nixos/modules/tasks/network-interfaces-systemd.nix
@@ -38,6 +38,12 @@ in
     } {
       assertion = cfg.vswitches == {};
       message = "networking.vswichtes are not supported by networkd.";
+    } {
+      assertion = cfg.defaultGateway == null || cfg.defaultGateway.interface == null;
+      message = "networking.defaultGateway.interface is not supported by networkd.";
+    } {
+      assertion = cfg.defaultGateway6 == null || cfg.defaultGateway6.interface == null;
+      message = "networking.defaultGateway6.interface is not supported by networkd.";
     } ] ++ flip mapAttrsToList cfg.bridges (n: { rstp, ... }: {
       assertion = !rstp;
       message = "networking.bridges.${n}.rstp is not supported by networkd.";
diff --git a/nixos/modules/tasks/network-interfaces.nix b/nixos/modules/tasks/network-interfaces.nix
index 83d9854d3517..3f56419d2a6d 100644
--- a/nixos/modules/tasks/network-interfaces.nix
+++ b/nixos/modules/tasks/network-interfaces.nix
@@ -116,6 +116,28 @@ let
       };
     };
 
+  gatewayCoerce = address: { inherit address; };
+
+  gatewayOpts = { ... }: {
+
+    options = {
+
+      address = mkOption {
+        type = types.str;
+        description = "The default gateway address.";
+      };
+
+      interface = mkOption {
+        type = types.nullOr types.str;
+        default = null;
+        example = "enp0s3";
+        description = "The default gateway interface.";
+      };
+
+    };
+
+  };
+
   interfaceOpts = { name, ... }: {
 
     options = {
@@ -327,19 +349,27 @@ in
 
     networking.defaultGateway = mkOption {
       default = null;
-      example = "131.211.84.1";
-      type = types.nullOr types.str;
+      example = {
+        address = "131.211.84.1";
+        device = "enp3s0";
+      };
+      type = types.nullOr (types.coercedTo types.str gatewayCoerce (types.submodule gatewayOpts));
       description = ''
-        The default gateway.  It can be left empty if it is auto-detected through DHCP.
+        The default gateway. It can be left empty if it is auto-detected through DHCP.
+        It can be specified as a string or an option set along with a network interface.
       '';
     };
 
     networking.defaultGateway6 = mkOption {
       default = null;
-      example = "2001:4d0:1e04:895::1";
-      type = types.nullOr types.str;
+      example = {
+        address = "2001:4d0:1e04:895::1";
+        device = "enp3s0";
+      };
+      type = types.nullOr (types.coercedTo types.str gatewayCoerce (types.submodule gatewayOpts));
       description = ''
-        The default ipv6 gateway.  It can be left empty if it is auto-detected through DHCP.
+        The default ipv6 gateway. It can be left empty if it is auto-detected through DHCP.
+        It can be specified as a string or an option set along with a network interface.
       '';
     };