diff --git a/tools/BUILD.gn b/tools/BUILD.gn
index 2eedb62..444d41e 100644
--- a/tools/BUILD.gn
+++ b/tools/BUILD.gn
@@ -182,7 +182,7 @@
     "//tools/qemu:tests($host_toolchain)",
     "//tools/rfc:tests",
     "//tools/sdk-tools:tests($host_toolchain)",
-    "//tools/shush:shush_test($host_toolchain)",
+    "//tools/shush:tests($host_toolchain)",
     "//tools/staticanalysis:tests",
     "//tools/symbol-index:tests",
     "//tools/symbolizer:tests",
diff --git a/tools/shush/BUILD.gn b/tools/shush/BUILD.gn
index 37f1cb8..cdfa1fe 100644
--- a/tools/shush/BUILD.gn
+++ b/tools/shush/BUILD.gn
@@ -5,38 +5,42 @@
 import("//build/rust/rustc_binary.gni")
 
 if (is_host) {
-  config("env") {
-    rustenv = [ "RUST_SYSROOT=$out_rustc_prefix" ]
-  }
+  _deps = [
+    "//third_party/rust_crates:anyhow",
+    "//third_party/rust_crates:argh",
+    "//third_party/rust_crates:lazy_static",
+    "//third_party/rust_crates:proc-macro2",
+    "//third_party/rust_crates:regex",
+    "//third_party/rust_crates:rustfix",
+    "//third_party/rust_crates:serde",
+    "//third_party/rust_crates:serde_json",
+    "//third_party/rust_crates:syn",
+  ]
+
+  _sources = [
+    "src/allow.rs",
+    "src/fix.rs",
+    "src/lint.rs",
+    "src/main.rs",
+    "src/owners.rs",
+    "src/span.rs",
+  ]
 
   rustc_binary("shush") {
     edition = "2021"
-    with_unit_tests = true
-    deps = [
-      "//third_party/rust_crates:anyhow",
-      "//third_party/rust_crates:argh",
-      "//third_party/rust_crates:lazy_static",
-      "//third_party/rust_crates:proc-macro2",
-      "//third_party/rust_crates:regex",
-      "//third_party/rust_crates:rustfix",
-      "//third_party/rust_crates:serde",
-      "//third_party/rust_crates:serde_json",
-      "//third_party/rust_crates:syn",
-    ]
-    sources = [
-      "src/allow.rs",
-      "src/fix.rs",
-      "src/lint.rs",
-      "src/main.rs",
-      "src/owners.rs",
-      "src/span.rs",
-    ]
+    deps = _deps
+    sources = _sources
+    rustenv = [ "RUST_SYSROOT=$out_rustc_prefix" ]
+  }
 
-    # Specify clippy-driver path from our prebuilts for tests
+  rustc_test("shush_test") {
+    edition = "2021"
+    deps = _deps
+    sources = _sources
+    source_root = "src/main.rs"
+
     test_deps = [ "//build/rust:prebuilt_toolchain_host_test_data" ]
-
-    # TODO(josephry): update this to just use rustenv after http://fxrev.dev/667908 lands
-    configs += [ ":env" ]
+    rustenv = [ "RUST_SYSROOT=$out_rustc_prefix" ]
   }
 
   copy("install") {
@@ -44,4 +48,9 @@
     deps = [ ":shush" ]
     outputs = [ "$root_build_dir/host-tools/{{source_file_part}}" ]
   }
+
+  group("tests") {
+    testonly = true
+    deps = [ ":shush_test" ]
+  }
 }
diff --git a/tools/shush/src/lint.rs b/tools/shush/src/lint.rs
index 0e54da4..b8746e9 100644
--- a/tools/shush/src/lint.rs
+++ b/tools/shush/src/lint.rs
@@ -19,24 +19,29 @@
     pub span: Span,
 }
 
-#[cfg(target_arch = "x86_64")]
-const HOST_ARCH: &str = "x64";
-#[cfg(target_arch = "aarch64")]
-const HOST_ARCH: &str = "arm64";
-#[cfg(target_os = "linux")]
-const HOST_OS: &str = "linux";
-#[cfg(target_os = "macos")]
-const HOST_OS: &str = "mac";
+#[allow(unused)]
+fn get_sysroot() -> String {
+    #[cfg(target_arch = "x86_64")]
+    const HOST_ARCH: &str = "x64";
+    #[cfg(target_arch = "aarch64")]
+    const HOST_ARCH: &str = "arm64";
+    #[cfg(target_os = "linux")]
+    const HOST_OS: &str = "linux";
+    #[cfg(target_os = "macos")]
+    const HOST_OS: &str = "mac";
+
+    #[cfg(test)]
+    let sysroot = env!("RUST_SYSROOT").to_owned();
+    #[cfg(not(test))]
+    let sysroot = format!("prebuilt/third_party/rust/{}-{}", HOST_OS, HOST_ARCH);
+
+    sysroot
+}
 
 /// Returns a mapping of the lint categories (all, style, etc.) to the individual
 /// names of the lints they contain by parsing the output of `clippy-driver -Whelp`.
 pub fn get_categories() -> HashMap<String, HashSet<String>> {
-    let sysroot = if cfg!(test) {
-        // TODO(josephry): update this to just use env! after http://fxrev.dev/667908 lands
-        option_env!("RUST_SYSROOT").unwrap().to_owned()
-    } else {
-        format!("prebuilt/third_party/rust/{}-{}", HOST_OS, HOST_ARCH)
-    };
+    let sysroot = get_sysroot();
     let output = Command::new(format!("{}/bin/clippy-driver", sysroot))
         .arg("--sysroot")
         .arg(&sysroot)
@@ -103,13 +108,11 @@
         .filter_map(|d| d.code.as_ref().map(|c| filter_lints.contains(&c.code).then(|| d.clone())))
         .flatten()
         .for_each(|lint| {
-            // The primary span is always last in the list
-            // TODO(josephry): Once rustfix 0.6.1 releases, use Diagnostic::is_primary
-            let span = lint.spans.last().expect("no spans found");
+            let span = lint.spans.iter().find(|s| s.is_primary).expect("no primary span found");
             let file = &span.file_name;
             // ignore stuff in the build directory
             if file.starts_with("out/") {
-                eprintln!("Ignoring file inside build dir: {}", span.file_name);
+                eprintln!("Ignoring file inside build dir: {}", file);
             } else {
                 files
                     .entry(file.to_string())