diff --git a/Cargo.lock b/Cargo.lock
index 33e35fc..041775a 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -79,6 +79,22 @@ version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0bca1619ff57dd7a56b58a8e25ef4199f123e78e503fe1653410350a1b98ae65"
 
+[[package]]
+name = "dissimilar"
+version = "1.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fc4b29f4b9bb94bf267d57269fd0706d343a160937108e9619fe380645428abb"
+
+[[package]]
+name = "expect-test"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2300477aab3a378f2ca00a4fbd4dc713654ab7ed790e4017493cb33656280633"
+dependencies = [
+ "dissimilar",
+ "once_cell",
+]
+
 [[package]]
 name = "heck"
 version = "0.3.3"
@@ -121,6 +137,7 @@ version = "0.5.0"
 dependencies = [
  "clap",
  "colorful",
+ "expect-test",
  "num_cpus",
  "pathdiff",
  "regex",
@@ -157,6 +174,12 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "once_cell"
+version = "1.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "692fcb63b64b1758029e0a96ee63e049ce8c5948587f2f7208df04625e5f6b56"
+
 [[package]]
 name = "pathdiff"
 version = "0.2.0"
diff --git a/default.nix b/default.nix
index 1c8c4da..a09535c 100644
--- a/default.nix
+++ b/default.nix
@@ -10,7 +10,7 @@ pkgs.rustPlatform.buildRustPackage {
   pname   = "nix-doc";
   version = "0.5.0";
 
-  cargoSha256 = "0jkn1rqiwjb8yr66h7mija5gkswvb379cc1wp6gq5dbb29ggxbj2";
+  cargoSha256 = "0xmw3fyic0fcg7a6z8dr3lv367bxqdhdrlrl2hhlz59xg5kq8b3f";
 
   src = gitignoreSource ./.;
 
diff --git a/nix-doc/src/tags.rs b/nix-doc/src/tags.rs
index 5417fc6..620dd72 100644
--- a/nix-doc/src/tags.rs
+++ b/nix-doc/src/tags.rs
@@ -359,7 +359,8 @@ mod tests {
     use super::*;
     use expect_test::{expect, Expect};
 
-    fn check(dir: PathBuf, expected: Expect) {
+    fn check(dir: &str, expected: Expect) {
+        let dir = PathBuf::from(dir);
         let curdir = current_dir().unwrap();
 
         println!("datadir: {}", &dir.display());
@@ -378,7 +379,7 @@ mod tests {
     #[test]
     fn smoke() {
         check(
-            PathBuf::from("testdata"),
+            "testdata",
             expect![[r#"
                 !_TAG_FILE_FORMAT	2	/extended format/
                 !_TAG_FILE_SORTED	1	/0=unsorted, 1=sorted, 2=foldcase/