diff --git a/packages/cowsay-yasunori/default.nix b/packages/cowsay-yasunori/default.nix
index fd3b541..3b3ddfa 100644
--- a/packages/cowsay-yasunori/default.nix
+++ b/packages/cowsay-yasunori/default.nix
@@ -7,6 +7,6 @@
 writeShellApplication {
   name = "${cowsay.pname}-yasunori";
   text = ''
-    ${yasunori-cli} | ${lib.getExe cowsay}
+    ${lib.getExe yasunori-cli} | ${lib.getExe cowsay};
   '';
 }
diff --git a/packages/kuusay/default.nix b/packages/kuusay/default.nix
index 914282a..81ad687 100644
--- a/packages/kuusay/default.nix
+++ b/packages/kuusay/default.nix
@@ -5,8 +5,11 @@
   cowsay,
 }:
 
-stdenv.mkDerivation (finalAttrs: {
+let
   pname = "kuusay";
+in
+stdenv.mkDerivation (finalAttrs: {
+  inherit pname;
   version = "1.0.0";
 
   src = lib.cleanSource ./.;
@@ -26,4 +29,5 @@ stdenv.mkDerivation (finalAttrs: {
     runHook postInstall
   '';
 
+
 })
diff --git a/packages/nikuussay/default.nix b/packages/nikuussay/default.nix
index 3255e2e..f37638d 100644
--- a/packages/nikuussay/default.nix
+++ b/packages/nikuussay/default.nix
@@ -5,8 +5,11 @@
   cowsay,
 }:
 
-stdenv.mkDerivation (finalAttrs: {
+let
   pname = "nikuussay";
+in
+stdenv.mkDerivation (finalAttrs: {
+  inherit pname;
   version = "1.0.0";
 
   src = lib.cleanSource ./.;
@@ -26,4 +29,6 @@ stdenv.mkDerivation (finalAttrs: {
     runHook postInstall
   '';
 
+  meta.mainProgram = pname;
+
 })
diff --git a/packages/yousay/default.nix b/packages/yousay/default.nix
index 2fdb419..b6e9ff0 100644
--- a/packages/yousay/default.nix
+++ b/packages/yousay/default.nix
@@ -5,8 +5,11 @@
   cowsay,
 }:
 
-stdenv.mkDerivation (finalAttrs: {
+let
   pname = "yousay";
+in
+stdenv.mkDerivation (finalAttrs: {
+  inherit pname;
   version = "1.0.0";
 
   src = lib.cleanSource ./.;
@@ -26,5 +29,6 @@ stdenv.mkDerivation (finalAttrs: {
     runHook postInstall
   '';
 
-})
+  meta.mainProgram = pname;
 
+})