diff --git a/pkgs/by-name/de/deno/package.nix b/pkgs/by-name/de/deno/package.nix
index c3abdb168673..64ab1a5847d0 100644
--- a/pkgs/by-name/de/deno/package.nix
+++ b/pkgs/by-name/de/deno/package.nix
@@ -213,13 +213,12 @@ rustPlatform.buildRustPackage (finalAttrs: {
   postInstall = ''
     # Remove non-essential binaries like denort and test_server
     find $out/bin/* -not -name "deno" -delete
-
-    ${lib.optionalString canExecute ''
-      installShellCompletion --cmd deno \
-        --bash <($out/bin/deno completions bash) \
-        --fish <($out/bin/deno completions fish) \
-        --zsh <($out/bin/deno completions zsh)
-    ''}
+  ''
+  + lib.optionalString canExecute ''
+    installShellCompletion --cmd deno \
+      --bash <($out/bin/deno completions bash) \
+      --fish <($out/bin/deno completions fish) \
+      --zsh <($out/bin/deno completions zsh)
   '';
 
   doInstallCheck = canExecute;