diff --git a/crates/uv-build/src/lib.rs b/crates/uv-build/src/lib.rs
index 3c0f1b469..479a4b35d 100644
--- a/crates/uv-build/src/lib.rs
+++ b/crates/uv-build/src/lib.rs
@@ -398,6 +398,7 @@ impl SourceBuild {
     pub async fn setup(
         source: &Path,
         subdirectory: Option<&Path>,
+        fallback_package_name: Option<&PackageName>,
         interpreter: &Interpreter,
         build_context: &impl BuildContext,
         source_build_context: SourceBuildContext,
@@ -422,10 +423,10 @@ impl SourceBuild {
         let (pep517_backend, project) =
             Self::extract_pep517_backend(&source_tree, &default_backend).map_err(|err| *err)?;
 
-        let package_name = project.clone().map(|p| p.name);
+        let package_name = project.as_ref().map(|p| &p.name).or(fallback_package_name);
 
         // Create a virtual environment, or install into the shared environment if requested.
-        let venv = if let Some(venv) = build_isolation.shared_environment(package_name.as_ref()) {
+        let venv = if let Some(venv) = build_isolation.shared_environment(package_name) {
             venv.clone()
         } else {
             uv_virtualenv::create_venv(
@@ -440,7 +441,7 @@ impl SourceBuild {
 
         // Setup the build environment. If build isolation is disabled, we assume the build
         // environment is already setup.
-        if build_isolation.is_isolated(package_name.as_ref()) {
+        if build_isolation.is_isolated(package_name) {
             let resolved_requirements = Self::get_resolved_requirements(
                 build_context,
                 source_build_context,
@@ -490,7 +491,7 @@ impl SourceBuild {
         // Create the PEP 517 build environment. If build isolation is disabled, we assume the build
         // environment is already setup.
         let runner = PythonRunner::new(concurrent_builds);
-        if build_isolation.is_isolated(package_name.as_ref()) {
+        if build_isolation.is_isolated(package_name) {
             create_pep517_build_environment(
                 &runner,
                 &source_tree,
diff --git a/crates/uv-dev/src/build.rs b/crates/uv-dev/src/build.rs
index 0b7a3584f..8170c2080 100644
--- a/crates/uv-dev/src/build.rs
+++ b/crates/uv-dev/src/build.rs
@@ -98,6 +98,7 @@ pub(crate) async fn build(args: BuildArgs) -> Result<PathBuf> {
     let builder = SourceBuild::setup(
         &args.sdist,
         args.subdirectory.as_deref(),
+        None,
         python.interpreter(),
         &build_dispatch,
         SourceBuildContext::default(),
diff --git a/crates/uv-dispatch/src/lib.rs b/crates/uv-dispatch/src/lib.rs
index 9b8134523..4a95d4554 100644
--- a/crates/uv-dispatch/src/lib.rs
+++ b/crates/uv-dispatch/src/lib.rs
@@ -298,11 +298,12 @@ impl<'a> BuildContext for BuildDispatch<'a> {
         dist: Option<&'data SourceDist>,
         build_kind: BuildKind,
     ) -> Result<SourceBuild> {
+        let dist_name = dist.map(distribution_types::Name::name);
         // Note we can only prevent builds by name for packages with names
         // unless all builds are disabled.
         if self
             .build_options
-            .no_build_requirement(dist.map(distribution_types::Name::name))
+            .no_build_requirement(dist_name)
             // We always allow editable builds
             && !matches!(build_kind, BuildKind::Editable)
         {
@@ -318,6 +319,7 @@ impl<'a> BuildContext for BuildDispatch<'a> {
         let builder = SourceBuild::setup(
             source,
             subdirectory,
+            dist_name,
             self.interpreter,
             self,
             self.source_build_context.clone(),