diff --git a/pkgs/oizys/oizys-go/cmd/boot.go b/pkgs/oizys/oizys-go/cmd/boot.go
index d3b7ba1..96e0826 100644
--- a/pkgs/oizys/oizys-go/cmd/boot.go
+++ b/pkgs/oizys/oizys-go/cmd/boot.go
@@ -5,16 +5,15 @@ import (
 	"oizys/pkg/oizys"
 )
 
-
-
 var bootCmd = &cobra.Command{
 	Use:   "boot",
 	Short: "nixos rebuild boot",
 	Run: func(cmd *cobra.Command, args []string) {
+		oizys.CheckFlake(flake)
 		oizys.NixosRebuild("boot", flake)
 	},
 }
 
 func init() {
-  rootCmd.AddCommand(bootCmd)
+	rootCmd.AddCommand(bootCmd)
 }
diff --git a/pkgs/oizys/oizys-go/cmd/build.go b/pkgs/oizys/oizys-go/cmd/build.go
index a7da2f0..7db8b75 100644
--- a/pkgs/oizys/oizys-go/cmd/build.go
+++ b/pkgs/oizys/oizys-go/cmd/build.go
@@ -5,17 +5,15 @@ import (
 	"oizys/pkg/oizys"
 )
 
-
 var buildCmd = &cobra.Command{
 	Use:   "build",
 	Short: "A brief description of your command",
 	Run: func(cmd *cobra.Command, args []string) {
+		oizys.CheckFlake(flake)
 		oizys.NixBuild(oizys.Output(flake, host), args...)
 	},
 }
 
-
-
 func init() {
-  rootCmd.AddCommand(buildCmd)
+	rootCmd.AddCommand(buildCmd)
 }
diff --git a/pkgs/oizys/oizys-go/cmd/cache.go b/pkgs/oizys/oizys-go/cmd/cache.go
index 93a0b87..97891e1 100644
--- a/pkgs/oizys/oizys-go/cmd/cache.go
+++ b/pkgs/oizys/oizys-go/cmd/cache.go
@@ -9,6 +9,7 @@ var cacheCmd = &cobra.Command{
 	Use:   "cache",
 	Short: "build and push to cachix",
 	Run: func(cmd *cobra.Command, args []string) {
+		oizys.CheckFlake(flake)
 		oizys.CacheBuild(oizys.Output(flake, host), cacheName, args...)
 	},
 }
@@ -16,10 +17,10 @@ var cacheCmd = &cobra.Command{
 func init() {
 	cacheCmd.Flags().StringVarP(
 		&cacheName,
-    "cache",
-    "c",
-    "daylin", 
-    "name of cachix binary cache",
+		"cache",
+		"c",
+		"daylin",
+		"name of cachix binary cache",
 	)
 	rootCmd.AddCommand(cacheCmd)
 }
diff --git a/pkgs/oizys/oizys-go/cmd/dry.go b/pkgs/oizys/oizys-go/cmd/dry.go
index 6783d35..1f6ac1d 100644
--- a/pkgs/oizys/oizys-go/cmd/dry.go
+++ b/pkgs/oizys/oizys-go/cmd/dry.go
@@ -1,19 +1,20 @@
 package cmd
 
 import (
+	"oizys/pkg/oizys"
 
-  "github.com/spf13/cobra"
-  "oizys/pkg/oizys"
+	"github.com/spf13/cobra"
 )
 
 var dryCmd = &cobra.Command{
 	Use:   "dry",
 	Short: "poor man's nix flake check",
 	Run: func(cmd *cobra.Command, args []string) {
+		oizys.CheckFlake(flake)
 		oizys.NixDryRun(oizys.Output(flake, host))
 	},
 }
 
 func init() {
-  rootCmd.AddCommand(dryCmd)
+	rootCmd.AddCommand(dryCmd)
 }
diff --git a/pkgs/oizys/oizys-go/cmd/output.go b/pkgs/oizys/oizys-go/cmd/output.go
index e00c521..c2a74f2 100644
--- a/pkgs/oizys/oizys-go/cmd/output.go
+++ b/pkgs/oizys/oizys-go/cmd/output.go
@@ -7,15 +7,15 @@ import (
 	"oizys/pkg/oizys"
 )
 
-
 var outputCmd = &cobra.Command{
 	Use:   "output",
 	Short: "show nixosConfiguration attr",
 	Run: func(cmd *cobra.Command, args []string) {
+		oizys.CheckFlake(flake)
 		fmt.Println(oizys.Output(flake, host))
 	},
 }
 
 func init() {
-  rootCmd.AddCommand(outputCmd)
+	rootCmd.AddCommand(outputCmd)
 }
diff --git a/pkgs/oizys/oizys-go/cmd/root.go b/pkgs/oizys/oizys-go/cmd/root.go
index b483dff..0d5ee98 100644
--- a/pkgs/oizys/oizys-go/cmd/root.go
+++ b/pkgs/oizys/oizys-go/cmd/root.go
@@ -1,9 +1,7 @@
 package cmd
 
 import (
-	"errors"
 	"fmt"
-	"io/fs"
 	"log"
 	"os"
 
@@ -21,10 +19,6 @@ func setFlake() {
 			flake = oizysDir
 		}
 	}
-
-	if _, err := os.Stat(flake); errors.Is(err, fs.ErrNotExist) {
-		log.Fatalln("path to flake:", flake, "does not exist")
-	}
 }
 
 func setHost() {
@@ -69,7 +63,6 @@ var rootCmd = &cobra.Command{
 	},
 }
 
-
 func init() {
 	rootCmd.CompletionOptions.HiddenDefaultCmd = true
 	rootCmd.PersistentFlags().StringVar(&flake, "flake", "", "path to flake ($OIZYS_DIR or $HOME/oizys)")
diff --git a/pkgs/oizys/oizys-go/cmd/switch.go b/pkgs/oizys/oizys-go/cmd/switch.go
index 9ccda3c..79e16a0 100644
--- a/pkgs/oizys/oizys-go/cmd/switch.go
+++ b/pkgs/oizys/oizys-go/cmd/switch.go
@@ -9,11 +9,11 @@ var switchCmd = &cobra.Command{
 	Use:   "switch",
 	Short: "nixos rebuild switch",
 	Run: func(cmd *cobra.Command, args []string) {
+		oizys.CheckFlake(flake)
 		oizys.NixosRebuild("switch", flake, args...)
 	},
 }
 
-
 func init() {
-  rootCmd.AddCommand(switchCmd)
+	rootCmd.AddCommand(switchCmd)
 }
diff --git a/pkgs/oizys/oizys-go/default.nix b/pkgs/oizys/oizys-go/default.nix
index 70f3043..1cc1e98 100644
--- a/pkgs/oizys/oizys-go/default.nix
+++ b/pkgs/oizys/oizys-go/default.nix
@@ -1,6 +1,9 @@
 {
+
+  installShellFiles,
   buildGoModule,
   lib,
+  ...
 }:
 buildGoModule {
   pname = "oizys";
@@ -8,4 +11,11 @@ buildGoModule {
 
   src = lib.cleanSource ./.;
   vendorHash = "sha256-kh/7dV49KaQcD9ho8IpBcRc6+05bn4XpMzAI9JXu7+o=";
+
+  nativeBuildInputs = [installShellFiles];
+
+  postInstall = ''
+    installShellCompletion --cmd oizys \
+      --zsh <($out/bin/oizys completion zsh)
+  '';
 }
diff --git a/pkgs/oizys/oizys-go/pkg/oizys/oizys.go b/pkgs/oizys/oizys-go/pkg/oizys/oizys.go
index 6b358cd..d905f80 100644
--- a/pkgs/oizys/oizys-go/pkg/oizys/oizys.go
+++ b/pkgs/oizys/oizys-go/pkg/oizys/oizys.go
@@ -1,7 +1,9 @@
 package oizys
 
 import (
+	"errors"
 	"fmt"
+	"io/fs"
 	"log"
 	"os"
 	"os/exec"
@@ -108,6 +110,12 @@ func CacheBuild(path string, cache string, rest ...string) {
 	runCommand(cmd)
 }
 
+func CheckFlake(flake string) {
+	if _, err := os.Stat(flake); errors.Is(err, fs.ErrNotExist) {
+		log.Fatalln("path to flake:", flake, "does not exist")
+	}
+}
+
 func Output(flake string, host string) string {
 	return fmt.Sprintf(
 		"%s#nixosConfigurations.%s.config.system.build.toplevel",