diff --git a/substrate/.gitlab-ci.yml b/substrate/.gitlab-ci.yml
index 0c06f3eb9c..bd75cb0bac 100644
--- a/substrate/.gitlab-ci.yml
+++ b/substrate/.gitlab-ci.yml
@@ -263,6 +263,20 @@ cargo-clippy:
   script:
     - SKIP_WASM_BUILD=1 env -u RUSTFLAGS cargo +nightly clippy --all-targets
 
+cargo-check-nixos:
+  stage:                           test
+  <<:                              *docker-env
+  <<:                              *test-refs
+  before_script:                   []
+  variables:
+    CI_IMAGE:                      "nixos/nix"
+    SNAP:                          "DUMMY"
+    WS_API:                        "DUMMY"
+  script:
+    - nix-channel --update
+    - nix-shell shell.nix
+    - nix-shell --run "cargo check --workspace --all-targets --all-features"
+
 cargo-check-benches:
   stage:                           test
   <<:                              *docker-env
diff --git a/substrate/shell.nix b/substrate/shell.nix
index 023946ce16..c318995605 100644
--- a/substrate/shell.nix
+++ b/substrate/shell.nix
@@ -5,7 +5,7 @@ let
       rev = "15b7a05f20aab51c4ffbefddb1b448e862dccb7d";
     });
   nixpkgs = import <nixpkgs> { overlays = [ mozillaOverlay ]; };
-  rust-nightly = with nixpkgs; ((rustChannelOf { date = "2022-02-10"; channel = "nightly"; }).rust.override {
+  rust-nightly = with nixpkgs; ((rustChannelOf { date = "2022-04-20"; channel = "nightly"; }).rust.override {
     extensions = [ "rust-src" ];
     targets = [ "wasm32-unknown-unknown" ];
   });
diff --git a/substrate/utils/frame/remote-externalities/src/lib.rs b/substrate/utils/frame/remote-externalities/src/lib.rs
index 018ad2f4e0..a717a93f07 100644
--- a/substrate/utils/frame/remote-externalities/src/lib.rs
+++ b/substrate/utils/frame/remote-externalities/src/lib.rs
@@ -1098,21 +1098,6 @@ mod remote_tests {
 		}
 	}
 
-	#[tokio::test]
-	async fn can_build_child_tree() {
-		init_logger();
-		Builder::<Block>::new()
-			.mode(Mode::Online(OnlineConfig {
-				transport: "wss://rpc.polkadot.io:443".to_owned().into(),
-				pallets: vec!["Crowdloan".to_owned()],
-				..Default::default()
-			}))
-			.build()
-			.await
-			.expect(REMOTE_INACCESSIBLE)
-			.execute_with(|| {});
-	}
-
 	#[tokio::test]
 	async fn can_create_child_snapshot() {
 		init_logger();
@@ -1196,9 +1181,7 @@ mod remote_tests {
 		init_logger();
 		Builder::<Block>::new()
 			.mode(Mode::Online(OnlineConfig {
-				// transport: "wss://kusama-rpc.polkadot.io".to_owned().into(),
-				transport: "ws://kianenigma-archive:9924".to_owned().into(),
-				// transport: "ws://localhost:9999".to_owned().into(),
+				transport: "wss://rpc.polkadot.io:443".to_owned().into(),
 				pallets: vec!["Crowdloan".to_owned()],
 				..Default::default()
 			}))