diff --git a/flake.nix b/flake.nix
index c7a1aaf..6037a7c 100644
--- a/flake.nix
+++ b/flake.nix
@@ -47,8 +47,13 @@
             config.mission-control.devShell
             config.flake-root.devShell
           ];
+          shellHook = ''
+            # For rust-analyzer 'hover' tooltips to work.
+            export RUST_SRC_PATH=${pkgs.rustPlatform.rustLibSrc}
+          '';
           nativeBuildInputs = [
             pkgs.cargo-watch
+            pkgs.rust-analyzer
           ];
         };