diff --git a/rust/treedirstate/.cargo/config b/.cargo/config
rename from rust/treedirstate/.cargo/config
rename to .cargo/config
diff --git a/Makefile b/Makefile
--- a/Makefile
+++ b/Makefile
@@ -15,7 +15,8 @@
 	$(PYTHON) setup.py \
 	  build_py -c -d . \
 	  build_clib \
-	  build_ext -i
+	  build_ext -i \
+	  build_rust_ext -i
 
 install:
 	$(PYTHON) setup.py $(PURE) install --prefix="$(PREFIX)" --force
diff --git a/setup.py b/setup.py
--- a/setup.py
+++ b/setup.py
@@ -2,6 +2,7 @@
 from distutils.cmd import Command
 from distutils.core import setup, Extension
 import distutils
+from distutils_rust import RustExtension, BuildRustExt
 import fnmatch
 from glob import glob
 
@@ -22,6 +23,25 @@
 OPTIMIZATION = "" if iswindows else "-O2"
 PRODUCEDEBUGSYMBOLS = "/DEBUG:FULL" if iswindows else "-g"
 
+if 'USERUST' in os.environ:
+    USERUST = int(os.environ['USERUST'])
+else:
+    import subprocess
+    USERUST = False
+    try:
+        cargo_version = subprocess.check_output(['cargo', '--version']).split()[1]
+    except Exception:
+        sys.stderr.write("not compiling Rust extensions: cargo is not available\n")
+    else:
+        required_cargo_version = '0.21'
+        if (LooseVersion(cargo_version) >= LooseVersion(required_cargo_version)):
+            USERUST = True
+        else:
+            sys.stderr.write(
+                    "not compiling Rust extensions: cargo is too old " +
+                    "(found %s, need %s or higher)\n"
+                    % (cargo_version, required_cargo_version))
+
 # whether to use Cython to recompile .pyx to .c/.cpp at build time.
 # if False, fallback to .c/.cpp in the repo and .pyx files are ignored.
 # if True, re-compile .c/.cpp from .pyx files, require cython at build time.
@@ -212,6 +232,10 @@
         'treemanifest',
         'linelog',
     ]
+    if USERUST:
+        availablepackages += [
+            'treedirstate',
+        ]
 
 def distutils_dir_name(dname):
     """Returns the name of a distutils build directory"""
@@ -496,6 +520,15 @@
             for name in fnmatch.filter(files, patten):
                 yield os.path.join(dirname, name)
 
+rust_ext_modules = []
+if USERUST:
+    rust_ext_modules.extend([
+        RustExtension('rusttreedirstate',
+            package='treedirstate',
+            manifest='rust/treedirstate/Cargo.toml',
+        ),
+    ])
+
 setup(
     name='fbhgext',
     version='1.0',
@@ -510,9 +543,11 @@
     packages=packages,
     install_requires=requires,
     py_modules=py_modules,
-    ext_modules = ext_modules,
+    ext_modules=ext_modules,
     libraries=libraries,
+    rust_ext_modules=rust_ext_modules,
     cmdclass={
         'clean_ext': CleanExtCommand,
+        'build_rust_ext': BuildRustExt,
     }
 )
diff --git a/treedirstate/Makefile b/treedirstate/Makefile
deleted file mode 100644
--- a/treedirstate/Makefile
+++ /dev/null
@@ -1,44 +0,0 @@
-NAME := rusttreedirstate
-
-# Cargo's depfiles use full paths, so we must include the full path
-# to the rust library.
-DIR := $(realpath $(join $(dir $(firstword $(MAKEFILE_LIST))),../rust/treedirstate))
-
-MODE ?= release
-
-ifeq ($(MODE),release)
-CARGO_ARGS += --release
-endif
-
-ifeq ($(shell uname),Darwin)
-LIBSUFFIX := .dylib
-else
-LIBSUFFIX := .so
-endif
-
-RUSTLIB := $(DIR)/target/$(MODE)/lib$(NAME)$(LIBSUFFIX)
-RUSTDEP := $(DIR)/target/$(MODE)/lib$(NAME).d
-
-.PHONY: all
-all: $(NAME).so
-
-$(NAME).so: $(RUSTLIB)
-	cp $< $@
-
-$(RUSTLIB):
-	cd $(DIR) && cargo build $(CARGO_ARGS)
-
-.PHONY: test
-test:
-	cd $(DIR) && cargo test
-
-.PHONY: clean
-clean:
-	$(RM) $(NAME).so
-	cd $(DIR) && cargo clean
-
-# This pattern rule for Rust source files forces a rebuild if any source file
-# is deleted.
-$(DIR)/src/%.rs: ;
-
--include $(RUSTDEP)