diff --git a/pkgs/applications/editors/vscode/extensions/default.nix b/pkgs/applications/editors/vscode/extensions/default.nix
index 2a36d7897879..49d933f647cf 100644
--- a/pkgs/applications/editors/vscode/extensions/default.nix
+++ b/pkgs/applications/editors/vscode/extensions/default.nix
@@ -2576,6 +2576,22 @@ let
         };
       };
 
+      lapo.asn1js = buildVscodeMarketplaceExtension {
+        mktplcRef = {
+          name = "asn1js";
+          publisher = "lapo";
+          version = "0.1.4";
+          hash = "sha256-utbIKlwNHnJZj/51f8hEDmUA/A26De/gY73iT4tXKRU=";
+        };
+        meta = {
+          description = "Decode ASN.1 content inside VSCode";
+          downloadPage = "https://marketplace.visualstudio.com/items?itemName=lapo.asn1js";
+          homepage = "https://github.com/lapo-luchini/vscode-asn1js";
+          maintainers = with lib.maintainers; [ katexochen ];
+          license = lib.licenses.isc;
+        };
+      };
+
       llvm-org.lldb-vscode = llvmPackages.lldb;
 
       llvm-vs-code-extensions.vscode-clangd = buildVscodeMarketplaceExtension {