diff --git a/crates/uv-distribution/src/metadata/lowering.rs b/crates/uv-distribution/src/metadata/lowering.rs
index 8c35f16bb..bd8f69971 100644
--- a/crates/uv-distribution/src/metadata/lowering.rs
+++ b/crates/uv-distribution/src/metadata/lowering.rs
@@ -208,12 +208,17 @@ pub(crate) fn lower_requirement(
                 .get(&requirement.name)
                 .ok_or(LoweringError::UndeclaredWorkspacePackage)?
                 .clone();
-            directory_source(
-                path.root(),
-                workspace.root(),
-                workspace.root(),
-                editable.unwrap_or(true),
-            )?
+            // The lockfile is relative to the workspace root.
+            let relative_to_workspace =
+                relative_to(path.root(), workspace.root()).map_err(LoweringError::RelativeTo)?;
+            let url = VerbatimUrl::parse_absolute_path(path.root())?
+                .with_given(relative_to_workspace.to_string_lossy());
+            RequirementSource::Directory {
+                install_path: path.root().clone(),
+                lock_path: relative_to_workspace,
+                url,
+                editable: editable.unwrap_or(true),
+            }
         }
         Source::CatchAll { .. } => {
             // Emit a dedicated error message, which is an improvement over Serde's default error.
@@ -274,33 +279,3 @@ fn path_source(
         })
     }
 }
-
-/// Convert a path string to a directory source.
-fn directory_source(
-    path: impl AsRef<Path>,
-    project_dir: &Path,
-    workspace_root: &Path,
-    editable: bool,
-) -> Result<RequirementSource, LoweringError> {
-    let path = path.as_ref();
-    let url = VerbatimUrl::parse_path(path, project_dir)?.with_given(path.to_string_lossy());
-    let absolute_path = path
-        .to_path_buf()
-        .absolutize_from(project_dir)
-        .map_err(|err| LoweringError::Absolutize(path.to_path_buf(), err))?
-        .to_path_buf();
-    let relative_to_workspace = if path.is_relative() {
-        // Relative paths in a project are relative to the project root, but the lockfile is
-        // relative to the workspace root.
-        relative_to(&absolute_path, workspace_root).map_err(LoweringError::RelativeTo)?
-    } else {
-        // If the user gave us an absolute path, we respect that.
-        path.to_path_buf()
-    };
-    Ok(RequirementSource::Directory {
-        install_path: absolute_path,
-        lock_path: relative_to_workspace,
-        url,
-        editable,
-    })
-}
diff --git a/crates/uv-fs/src/path.rs b/crates/uv-fs/src/path.rs
index 0c361915b..2a48259f6 100644
--- a/crates/uv-fs/src/path.rs
+++ b/crates/uv-fs/src/path.rs
@@ -332,8 +332,9 @@ pub fn relative_to(path: impl AsRef<Path>, base: impl AsRef<Path>) -> Result<Pat
         .as_ref()
         .ancestors()
         .find_map(|ancestor| {
-            path.as_ref()
-                .strip_prefix(ancestor)
+            // Simplifying removes the UNC path prefix on windows.
+            dunce::simplified(path.as_ref())
+                .strip_prefix(dunce::simplified(ancestor))
                 .ok()
                 .map(|stripped| (stripped, ancestor))
         })
@@ -342,8 +343,8 @@ pub fn relative_to(path: impl AsRef<Path>, base: impl AsRef<Path>) -> Result<Pat
                 io::ErrorKind::Other,
                 format!(
                     "Trivial strip failed: {} vs. {}",
-                    path.simplified_display(),
-                    base.simplified_display()
+                    path.as_ref().simplified_display(),
+                    base.as_ref().simplified_display()
                 ),
             )
         })?;
diff --git a/crates/uv-resolver/src/manifest.rs b/crates/uv-resolver/src/manifest.rs
index 1952e0273..22ae0df8b 100644
--- a/crates/uv-resolver/src/manifest.rs
+++ b/crates/uv-resolver/src/manifest.rs
@@ -100,39 +100,40 @@ impl Manifest {
     ) -> impl Iterator<Item = &Requirement> + 'a {
         match mode {
             // Include all direct and transitive requirements, with constraints and overrides applied.
-            DependencyMode::Transitive => Either::Left( self
-                .lookaheads
-                .iter()
-                .flat_map(move |lookahead| {
-                    self.overrides
-                        .apply(lookahead.requirements())
-                        .filter(move |requirement| {
-                            requirement.evaluate_markers(markers, lookahead.extras())
-                        })
-                })
-                .chain(
-                    self.overrides
-                        .apply(&self.requirements)
-                        .filter(move |requirement| requirement.evaluate_markers(markers, &[])),
-                )
-                .chain(
-                    self.constraints
-                        .requirements()
-                        .filter(move |requirement| requirement.evaluate_markers(markers, &[])),
-                )
-                .chain(
-                    self.overrides
-                        .requirements()
-                        .filter(move |requirement| requirement.evaluate_markers(markers, &[])),
-                ))
-            ,
-
+            DependencyMode::Transitive => Either::Left(
+                self.lookaheads
+                    .iter()
+                    .flat_map(move |lookahead| {
+                        self.overrides
+                            .apply(lookahead.requirements())
+                            .filter(move |requirement| {
+                                requirement.evaluate_markers(markers, lookahead.extras())
+                            })
+                    })
+                    .chain(
+                        self.overrides
+                            .apply(&self.requirements)
+                            .filter(move |requirement| requirement.evaluate_markers(markers, &[])),
+                    )
+                    .chain(
+                        self.constraints
+                            .requirements()
+                            .filter(move |requirement| requirement.evaluate_markers(markers, &[])),
+                    )
+                    .chain(
+                        self.overrides
+                            .requirements()
+                            .filter(move |requirement| requirement.evaluate_markers(markers, &[])),
+                    ),
+            ),
             // Include direct requirements, with constraints and overrides applied.
             DependencyMode::Direct => Either::Right(
-                self.overrides.apply(&self.requirements)
-                .chain(self.constraints.requirements())
-                .chain(self.overrides.requirements())
-                .filter(move |requirement| requirement.evaluate_markers(markers, &[]))),
+                self.overrides
+                    .apply(&self.requirements)
+                    .chain(self.constraints.requirements())
+                    .chain(self.overrides.requirements())
+                    .filter(move |requirement| requirement.evaluate_markers(markers, &[])),
+            ),
         }
     }