diff --git a/flake.nix b/flake.nix
index df8420d..0c04048 100644
--- a/flake.nix
+++ b/flake.nix
@@ -1,7 +1,7 @@
 {
   inputs = {
-    nixpkgs-unstable.url = "github:nixos/nixpkgs/nixos-unstable";
-    nixpkgs.url = "github:NixOS/nixpkgs/nixos-25.05";
+    nixpkgs-unstable.url = "github:nixos/nixpkgs?ref=nixos-unstable";
+    nixpkgs.url = "github:NixOS/nixpkgs?ref=nixos-25.05";
 
     flake-utils.url = "github:numtide/flake-utils";
 
@@ -10,7 +10,7 @@
       inputs.nixpkgs.follows = "nixpkgs";
     };
 
-    nixos-hardware.url = "github:NixOS/nixos-hardware/master";
+    nixos-hardware.url = "github:NixOS/nixos-hardware?ref=master";
 
     microvm = {
       url = "github:astro/microvm.nix";
@@ -21,7 +21,7 @@
     };
 
     lanzaboote = {
-      url = "github:nix-community/lanzaboote/v0.4.2";
+      url = "github:nix-community/lanzaboote?ref=v0.4.2";
       inputs.nixpkgs.follows = "nixpkgs-unstable";
     };