diff --git a/src/fs.rs b/src/fs.rs
index 63932bdbaa..ab6cb8eb1a 100644
--- a/src/fs.rs
+++ b/src/fs.rs
@@ -81,7 +81,8 @@ pub fn normalize_path_to<P: AsRef<Path>, R: AsRef<Path>>(path: P, project_root:
 }
 
 /// Convert an absolute path to be relative to the current working directory.
-pub fn relativize_path(path: &Path) -> String {
+pub fn relativize_path(path: impl AsRef<Path>) -> String {
+    let path = path.as_ref();
     if let Ok(path) = path.strip_prefix(&*path_dedot::CWD) {
         return format!("{}", path.display());
     }
diff --git a/src/rules/flake8_no_pep420/rules.rs b/src/rules/flake8_no_pep420/rules.rs
index 7791e4a09d..52ef33806d 100644
--- a/src/rules/flake8_no_pep420/rules.rs
+++ b/src/rules/flake8_no_pep420/rules.rs
@@ -21,6 +21,10 @@ impl Violation for ImplicitNamespacePackage {
 /// INP001
 pub fn implicit_namespace_package(path: &Path, package: Option<&Path>) -> Option<Diagnostic> {
     if package.is_none() && path.extension().map_or(true, |ext| ext != "pyi") {
+        #[cfg(all(test, windows))]
+        let path = path
+            .to_string_lossy()
+            .replace(std::path::MAIN_SEPARATOR, "/"); // The snapshot test expects / as the path separator.
         Some(Diagnostic::new(
             ImplicitNamespacePackage(fs::relativize_path(path)),
             Range::default(),