diff --git a/flake.nix b/flake.nix
index 2033a51..f95d1a0 100644
--- a/flake.nix
+++ b/flake.nix
@@ -3,6 +3,7 @@
 
   inputs = {
     nixpkgs.url = "github:NixOS/nixpkgs/nixos-21.11";
+    nixpkgs-unstable.url = "github:NixOS/nixpkgs/nixos-unstable";
     rust-overlay.url = "github:oxalica/rust-overlay";
     flake-utils.url = "github:numtide/flake-utils";
     flake-compat = {
@@ -15,11 +16,12 @@
     };
   };
 
-  outputs = { self, nixpkgs, flake-utils, flake-compat, gitignoresrc, rust-overlay, ... }@inputs:
+  outputs = { self, nixpkgs, nixpkgs-unstable, flake-utils, flake-compat, gitignoresrc, rust-overlay, ... }@inputs:
     {
       #overlay = import ./nix { inherit gitignoresrc; };
     } // (flake-utils.lib.eachDefaultSystem (system:
       let
+        unstable = import nixpkgs-unstable { inherit system; };
         pkgs = import nixpkgs {
           inherit system;
           overlays = [ (import rust-overlay)];
@@ -33,7 +35,7 @@
             buildInputs = [
               pkgs.rust-bin.nightly.latest.rustfmt
               pkgs.rust-bin.stable.latest.default
-              pkgs.rust-analyzer
+              unstable.rust-analyzer
               pkgs.cargo-audit
               pkgs.cargo-license
               pkgs.cargo-tarpaulin
diff --git a/lib/src/datatypes/adf.rs b/lib/src/datatypes/adf.rs
index b3ed041..e6e4edd 100644
--- a/lib/src/datatypes/adf.rs
+++ b/lib/src/datatypes/adf.rs
@@ -216,7 +216,7 @@ impl ThreeValuedInterpretationsIterator {
         }
     }
 
-    fn decrement_vec(vector: &mut Vec<usize>) -> bool {
+    fn decrement_vec(vector: &mut [usize]) -> bool {
         let mut cur_pos = None;
         for (idx, value) in vector.iter_mut().enumerate() {
             if *value > 0 {