diff --git a/lib.nix b/lib.nix
index 525940e..d390997 100644
--- a/lib.nix
+++ b/lib.nix
@@ -17,7 +17,7 @@ let
     } // config.flake;
 
   mkShell = config: pkgs: system:
-    pkgs.mkShell {
+    config.mkShell {
       packages = config.packages ++ [ config.formatter ];
       LD_LIBRARY_PATH = makeLibraryPath config.libraries;
       inputsFrom = attrValues (config.flake.packages.${system} or { });
diff --git a/modules/top-level.nix b/modules/top-level.nix
index 5f96c7c..e88ee96 100644
--- a/modules/top-level.nix
+++ b/modules/top-level.nix
@@ -69,6 +69,18 @@ in
         This is mainly for conch modules; shellHook should generally be used instead.
       '';
     };
+
+    mkShell = mkOption {
+      # can't represent `f :: set -> drv` with option type system
+      type = with types; anything;
+      default = pkgs.mkShell;
+      example = [ "craneLib.devShell" ];
+      description = mdDoc ''
+        A function compatible with `pkgs.mkShell`, to allow arbitrary extending of use-case.
+
+        Specifically made for crane's `craneLib.devShell`.
+      '';
+    };
   };
 
   config._module = {