diff --git a/src/fromager/build_environment.py b/src/fromager/build_environment.py
index e51a8c30..1be2fe5b 100644
--- a/src/fromager/build_environment.py
+++ b/src/fromager/build_environment.py
@@ -93,8 +93,9 @@ def __init__(
         self._ctx = ctx
         self._req = req
         self._sdist_root_dir = sdist_root_dir
+        # abiflags adds 't' for free-threaded (nogil) builds
         self.path = sdist_root_dir.parent.absolute().joinpath(
-            f"build-{platform.python_version()}"
+            f"build-{platform.python_version()}{sys.abiflags}"
         )
         self._createenv()