diff --git a/default.nix b/default.nix
index c6e9684..3b3d531 100644
--- a/default.nix
+++ b/default.nix
@@ -124,7 +124,9 @@ let
   ## Get the installable application (only static executable):
   thisApp = mkHaskellApp {
     drv = thisHaskell.${thisHaskellPackages.main.name};
-    binPaths = [ ];
+    binPaths = [
+      pkgs.bashInteractive ## Added for bash-based CLI option completions
+    ];
   };
 
   ############
diff --git a/nix/lib/mk-haskell-app.nix b/nix/lib/mk-haskell-app.nix
index caf46c1..5f94492 100644
--- a/nix/lib/mk-haskell-app.nix
+++ b/nix/lib/mk-haskell-app.nix
@@ -10,6 +10,7 @@ let
   ## We need these inputs at buildtime:
   extraNativeBuildInputs = [
     pkgs.git
+    pkgs.installShellFiles
     pkgs.makeWrapper
     pkgs.ronn
   ] ++ nativeBuildInputs;
@@ -21,6 +22,11 @@ let
   extraPostFixup = ''
     ## Wrap program:
     wrapProgram $out/bin/${name} --prefix PATH : ${binPath}
+
+    ## Install completion scripts:
+    installShellCompletion --bash --name ${name}.bash <($out/bin/${name} --bash-completion-script "$out/bin/${name}")
+    installShellCompletion --fish --name ${name}.fish <($out/bin/${name} --fish-completion-script "$out/bin/${name}")
+    installShellCompletion --zsh  --name _${name}     <($out/bin/${name} --zsh-completion-script  "$out/bin/${name}")
   '';
 in
 pkgs.haskell.lib.justStaticExecutables (