diff --git a/nixos/modules/misc/documentation.nix b/nixos/modules/misc/documentation.nix
index 8f09568ee093..bb294addccd9 100644
--- a/nixos/modules/misc/documentation.nix
+++ b/nixos/modules/misc/documentation.nix
@@ -207,8 +207,19 @@ in
   };
 
   config = mkIf cfg.enable (mkMerge [
+    {
+      assertions = [
+        {
+          assertion = !(cfg.man.man-db.enable && cfg.man.mandoc.enable);
+          message = ''
+            man-db and mandoc can't be used as the default man page viewer at the same time!
+          '';
+        }
+      ];
+    }
 
-    # The actual implementation for this lives in man-db.nix
+    # The actual implementation for this lives in man-db.nix or mandoc.nix,
+    # depending on which backend is active.
     (mkIf cfg.man.enable {
       environment.pathsToLink = [ "/share/man" ];
       environment.extraOutputsToInstall = [ "man" ] ++ optional cfg.dev.enable "devman";
diff --git a/nixos/modules/misc/mandoc.nix b/nixos/modules/misc/mandoc.nix
new file mode 100644
index 000000000000..939f87a31784
--- /dev/null
+++ b/nixos/modules/misc/mandoc.nix
@@ -0,0 +1,51 @@
+{ config, lib, pkgs, ... }:
+
+let
+  makewhatis = "${lib.getBin pkgs.mandoc}/bin/makewhatis";
+
+  cfg = config.documentation.man.mandoc;
+
+in {
+  meta.maintainers = [ lib.maintainers.sternenseemann ];
+
+  options = {
+    documentation.man.mandoc = {
+      enable = lib.mkEnableOption "mandoc as the default man page viewer";
+
+      manPath = lib.mkOption {
+        type = with lib.types; listOf str;
+        default = [ "share/man" ];
+        example = lib.literalExpression "[ \"share/man\" \"share/man/fr\" ]";
+        description = ''
+          Change the manpath, i. e. the directories where
+          <citerefentry><refentrytitle>man</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+          looks for section-specific directories of man pages.
+          You only need to change this setting if you want extra man pages
+          (e. g. in non-english languages). All values must be strings that
+          are a valid path from the target prefix (without including it).
+          The first value given takes priority.
+        '';
+      };
+    };
+  };
+
+  config = lib.mkIf cfg.enable {
+    environment = {
+      systemPackages = [ pkgs.mandoc ];
+
+      # tell mandoc about man pages
+      etc."man.conf".text = lib.concatMapStrings (path: ''
+        manpath /run/current-system/sw/${path}
+      '') cfg.manPath;
+
+      # create mandoc.db for whatis(1), apropos(1) and man(1) -k
+      # TODO(@sternenseemman): fix symlinked directories not getting indexed,
+      # see: https://inbox.vuxu.org/mandoc-tech/20210906171231.GF83680@athene.usta.de/T/#e85f773c1781e3fef85562b2794f9cad7b2909a3c
+      extraSetup = lib.mkIf config.documentation.man.generateCaches ''
+        ${makewhatis} -T utf8 ${
+          lib.concatMapStringsSep " " (path: "\"$out/${path}\"") cfg.manPath
+        }
+      '';
+    };
+  };
+}