diff --git a/integration-tests/default.nix b/integration-tests/default.nix
index 4fdaa39..a9453a2 100644
--- a/integration-tests/default.nix
+++ b/integration-tests/default.nix
@@ -8,8 +8,18 @@
   apply-local = import ./apply-local { inherit pkgs; };
   build-on-target = import ./build-on-target { inherit pkgs; };
   exec = import ./exec { inherit pkgs; };
-  flakes = import ./flakes { inherit pkgs; };
-  flakes-streaming = import ./flakes { inherit pkgs; evaluator = "streaming"; };
+
+  # FIXME: The old evaluation method doesn't work purely with Nix 2.21+
+  flakes = import ./flakes {
+    inherit pkgs;
+    extraApplyFlags = "--experimental-flake-eval";
+  };
+  flakes-impure = import ./flakes {
+    inherit pkgs;
+    pure = false;
+  };
+  #flakes-streaming = import ./flakes { inherit pkgs; evaluator = "streaming"; };
+
   parallel = import ./parallel { inherit pkgs; };
 
   allow-apply-all = import ./allow-apply-all { inherit pkgs; };
diff --git a/integration-tests/flakes/default.nix b/integration-tests/flakes/default.nix
index 2f3f3c7..8938310 100644
--- a/integration-tests/flakes/default.nix
+++ b/integration-tests/flakes/default.nix
@@ -1,13 +1,29 @@
 { pkgs
 , evaluator ? "chunked"
+, extraApplyFlags ? ""
+, pure ? true
 }:
 
 let
+  inherit (pkgs) lib;
+
   tools = pkgs.callPackage ../tools.nix {
     targets = [ "alpha" ];
   };
+
+  applyFlags = "--evaluator ${evaluator} ${extraApplyFlags}"
+    + lib.optionalString (!pure) "--impure";
+
+  # From integration-tests/nixpkgs.nix
+  colmenaFlakeInputs = pkgs._inputs;
 in tools.runTest {
-  name = "colmena-flakes-${evaluator}";
+  name = "colmena-flakes-${evaluator}"
+    + lib.optionalString (!pure) "-impure";
+
+  nodes.deployer = {
+    virtualisation.additionalPaths =
+      lib.mapAttrsToList (k: v: v.outPath) colmenaFlakeInputs;
+  };
 
   colmena.test = {
     bundle = ./.;
@@ -16,12 +32,13 @@ in tools.runTest {
       import re
 
       deployer.succeed("sed -i 's @nixpkgs@ path:${pkgs._inputs.nixpkgs.outPath}?narHash=${pkgs._inputs.nixpkgs.narHash} g' /tmp/bundle/flake.nix")
+      deployer.succeed("sed -i 's @colmena@ path:${tools.colmena.src} g' /tmp/bundle/flake.nix")
 
       with subtest("Lock flake dependencies"):
           deployer.succeed("cd /tmp/bundle && nix --extra-experimental-features \"nix-command flakes\" flake lock")
 
       with subtest("Deploy with a plain flake without git"):
-          deployer.succeed("cd /tmp/bundle && ${tools.colmenaExec} apply --on @target --evaluator ${evaluator}")
+          deployer.succeed("cd /tmp/bundle && ${tools.colmenaExec} apply --on @target ${applyFlags}")
           alpha.succeed("grep FIRST /etc/deployment")
 
       with subtest("Deploy with a git flake"):
@@ -29,21 +46,22 @@ in tools.runTest {
 
           # don't put probe.nix in source control - should fail
           deployer.succeed("cd /tmp/bundle && git init && git add flake.nix flake.lock hive.nix tools.nix")
-          logs = deployer.fail("cd /tmp/bundle && run-copy-stderr ${tools.colmenaExec} apply --on @target --evaluator ${evaluator}")
+          logs = deployer.fail("cd /tmp/bundle && run-copy-stderr ${tools.colmenaExec} apply --on @target ${applyFlags}")
           assert re.search(r"probe.nix.*No such file or directory", logs)
 
           # now it should succeed
           deployer.succeed("cd /tmp/bundle && git add probe.nix")
-          deployer.succeed("cd /tmp/bundle && ${tools.colmenaExec} apply --on @target --evaluator ${evaluator}")
+          deployer.succeed("cd /tmp/bundle && ${tools.colmenaExec} apply --on @target ${applyFlags}")
           alpha.succeed("grep SECOND /etc/deployment")
 
+    '' + lib.optionalString pure ''
       with subtest("Check that impure expressions are forbidden"):
           deployer.succeed("sed -i 's|SECOND|''${builtins.readFile /etc/hostname}|g' /tmp/bundle/probe.nix")
-          logs = deployer.fail("cd /tmp/bundle && run-copy-stderr ${tools.colmenaExec} apply --on @target --evaluator ${evaluator}")
+          logs = deployer.fail("cd /tmp/bundle && run-copy-stderr ${tools.colmenaExec} apply --on @target ${applyFlags}")
           assert re.search(r"access to absolute path.*forbidden in pure eval mode", logs)
 
       with subtest("Check that impure expressions can be allowed with --impure"):
-          deployer.succeed("cd /tmp/bundle && ${tools.colmenaExec} apply --on @target --evaluator ${evaluator} --impure")
+          deployer.succeed("cd /tmp/bundle && ${tools.colmenaExec} apply --on @target ${applyFlags} --impure")
           alpha.succeed("grep deployer /etc/deployment")
     '';
   };
diff --git a/integration-tests/flakes/flake.nix b/integration-tests/flakes/flake.nix
index 4924867..3346774 100644
--- a/integration-tests/flakes/flake.nix
+++ b/integration-tests/flakes/flake.nix
@@ -3,13 +3,15 @@
 
   inputs = {
     nixpkgs.url = "@nixpkgs@";
+    colmena.url = "@colmena@";
   };
 
-  outputs = { self, nixpkgs }: let
+  outputs = { self, nixpkgs, colmena }: let
     pkgs = import nixpkgs {
       system = "x86_64-linux";
     };
   in {
     colmena = import ./hive.nix { inherit pkgs; };
+    colmenaHive = colmena.lib.makeHive self.outputs.colmena;
   };
 }