diff --git a/docs/docs/plugin.md b/docs/docs/plugin.md
index a98d47dc63634ef9bb34ec400ae9e6d45234bbe2..926737d33580411f1634d7c0e6875811ae34b4e1 100644
--- a/docs/docs/plugin.md
+++ b/docs/docs/plugin.md
@@ -125,7 +125,7 @@ which are not covered in the above example:
 - `core.repository_class`: change the class of repository object, which controls how to look for candidates and metadata of a package
 - `core.resolver_class`: change the resolver class, to control the resolution process
 - `core.synchronizer_class`: change the synchronizer_class, to control the installation process
-- `core.parser = None`: add arguments to the **root** argument parser
+- `core.parser`: add arguments to the **root** argument parser
 
 ## Publish your plugin
 
diff --git a/news/81.bugfix b/news/81.bugfix
new file mode 100644
index 0000000000000000000000000000000000000000..f994c546f26091fa4143a44d1c3b117f88120f7d
--- /dev/null
+++ b/news/81.bugfix
@@ -0,0 +1 @@
+Fix wheel builds when `package_dir` is mapped.
diff --git a/news/81.feature b/news/81.feature
new file mode 100644
index 0000000000000000000000000000000000000000..9d62f484d8824a39ab7f22ce98465a090ebd2eab
--- /dev/null
+++ b/news/81.feature
@@ -0,0 +1 @@
+Add test cases for `pdm build`.
diff --git a/pdm/builders/base.py b/pdm/builders/base.py
index f3d73648e0f44494a6358d1fa67c95b9e3a5b01a..ef3208309f883444b83728701fc0fc675a02ce91 100644
--- a/pdm/builders/base.py
+++ b/pdm/builders/base.py
@@ -72,9 +72,9 @@ def _merge_globs(include_globs, excludes_globs):
     return includes, excludes
 
 
-def _find_top_packages() -> List[str]:
+def _find_top_packages(root) -> List[str]:
     result = []
-    for path in os.listdir("."):
+    for path in os.listdir(root):
         if (
             os.path.isdir(path)
             and os.path.exists(os.path.join(path, "__init__.py"))
@@ -111,6 +111,7 @@ class Builder:
         self.ireq = ireq
         self.project = Project(ireq.unpacked_source_directory)
         self._old_cwd = None
+        self.package_dir = None
 
     def __enter__(self) -> "Builder":
         self._old_cwd = os.getcwd()
@@ -134,11 +135,17 @@ class Builder:
         dont_find_froms = []
 
         if not self.meta.includes:
-            find_froms = ["src"] if os.path.isdir("src") else _find_top_packages()
+            if os.path.isdir("src"):
+                find_froms = ["src"]
+                self.package_dir = "src"
+            else:
+                find_froms = _find_top_packages(".")
             if not find_froms:
                 includes = ["*.py"]
         else:
             for pat in self.meta.includes:
+                if os.path.basename(pat) == "*":
+                    pat = pat[:-2]
                 if "*" in pat or os.path.isfile(pat):
                     includes.append(pat)
                 else:
@@ -157,6 +164,12 @@ class Builder:
         includes, excludes = _merge_globs(include_globs, excludes_globs)
 
         for path in find_froms:
+            if (
+                not os.path.isfile(os.path.join(path, "__init__.py"))
+                and _find_top_packages(path)
+                and not self.package_dir
+            ):
+                self.package_dir = path
 
             for root, dirs, filenames in os.walk(path):
                 if root == "__pycache__" or any(
@@ -189,7 +202,7 @@ class Builder:
         if self.project.pyproject_file.exists():
             yield "pyproject.toml"
 
-    def find_files_to_add(self, include_build: bool = False) -> List[str]:
+    def find_files_to_add(self, include_build: bool = False) -> List[Path]:
         """Traverse the project path and return a list of file names
         that should be included in a sdist distribution.
         If include_build is True, will include files like LICENSE, README and pyproject
diff --git a/pdm/builders/wheel.py b/pdm/builders/wheel.py
index abdde2ed3e5d7957586e59901d2e2df7f38fa37f..7deb73b393f882f0ce32353dab7b8ffccbc221f9 100644
--- a/pdm/builders/wheel.py
+++ b/pdm/builders/wheel.py
@@ -182,7 +182,13 @@ class WheelBuilder(Builder):
 
     def _copy_module(self, wheel):
         for path in self.find_files_to_add():
-            self._add_file(wheel, str(path))
+            rel_path = None
+            if self.package_dir:
+                try:
+                    rel_path = path.relative_to(self.package_dir).as_posix()
+                except ValueError:
+                    pass
+            self._add_file(wheel, str(path), rel_path)
 
     def _add_file(self, wheel, full_path, rel_path=None):
         if not rel_path:
diff --git a/pdm/cli/actions.py b/pdm/cli/actions.py
index 0095529dd6ae69898bfd00c19e39200a950d7a7d..4fe1e4e80aaeb6552eae74371854e1de49c86573 100644
--- a/pdm/cli/actions.py
+++ b/pdm/cli/actions.py
@@ -378,7 +378,7 @@ def do_build(
         stream.echo("All artifacts are disabled, nothing to do.", err=True)
         return
     ireq = project.make_self_candidate(False).ireq
-    ireq.source_dir = "."
+    ireq.source_dir = project.root.as_posix()
     if clean:
         shutil.rmtree(dest, ignore_errors=True)
     if sdist:
diff --git a/pdm/project/meta.py b/pdm/project/meta.py
index e3586b4c7ade26994baa1ae171e36c7a6629a855..ac1e9936c4a3958b3d2f53fd421ba2bf90b96027 100644
--- a/pdm/project/meta.py
+++ b/pdm/project/meta.py
@@ -48,7 +48,7 @@ class PackageMeta:
         if isinstance(value, str):
             return value
         version_source = value.get("from")
-        with open(version_source, encoding="utf-8") as fp:
+        with self.project.root.joinpath(version_source).open(encoding="utf-8") as fp:
             version = re.findall(
                 r"^__version__\s*=\s*[\"'](.+?)[\"']\s*$", fp.read(), re.M
             )[0]
diff --git a/tests/cli/test_build.py b/tests/cli/test_build.py
new file mode 100644
index 0000000000000000000000000000000000000000..0845271e968468da5d52cdad662e26302dd31bb2
--- /dev/null
+++ b/tests/cli/test_build.py
@@ -0,0 +1,115 @@
+import tarfile
+import zipfile
+
+from distlib.wheel import Wheel
+
+from pdm.cli import actions
+
+
+def get_tarball_names(path):
+    with tarfile.open(path, "r:gz") as tar:
+        return tar.getnames()
+
+
+def get_wheel_names(path):
+    with zipfile.ZipFile(path) as zf:
+        return zf.namelist()
+
+
+def test_build_single_module(fixture_project):
+    project = fixture_project("demo-module")
+    assert project.meta.version == "0.1.0"
+
+    actions.do_build(project)
+    tar_names = get_tarball_names(project.root / "dist/demo-module-0.1.0.tar.gz")
+    for name in [
+        "foo_module.py",
+        "bar_module.py",
+        "LICENSE",
+        "pyproject.toml",
+        "PKG-INFO",
+    ]:
+        assert f"demo-module-0.1.0/{name}" in tar_names
+
+    zip_names = get_wheel_names(
+        project.root / "dist/demo_module-0.1.0-py3-none-any.whl"
+    )
+    for name in ["foo_module.py", "bar_module.py"]:
+        assert name in zip_names
+
+    for name in ("pyproject.toml", "LICENSE"):
+        assert name not in zip_names
+
+    assert Wheel(
+        (project.root / "dist/demo_module-0.1.0-py3-none-any.whl").as_posix()
+    ).metadata
+
+
+def test_build_single_module_with_readme(fixture_project):
+    project = fixture_project("demo-module")
+    project.tool_settings["readme"] = "README.md"
+    project.write_pyproject()
+    actions.do_build(project)
+    assert "demo-module-0.1.0/README.md" in get_tarball_names(
+        project.root / "dist/demo-module-0.1.0.tar.gz"
+    )
+
+
+def test_build_package(fixture_project):
+    project = fixture_project("demo-package")
+    actions.do_build(project)
+
+    tar_names = get_tarball_names(project.root / "dist/demo-package-0.1.0.tar.gz")
+    assert "demo-package-0.1.0/my_package/__init__.py" in tar_names
+    assert "demo-package-0.1.0/my_package/data.json" in tar_names
+    assert "demo-package-0.1.0/single_module.py" not in tar_names
+    assert "demo-package-0.1.0/data_out.json" not in tar_names
+
+    zip_names = get_wheel_names(
+        project.root / "dist/demo_package-0.1.0-py3-none-any.whl"
+    )
+    assert "my_package/__init__.py" in zip_names
+    assert "my_package/data.json" in zip_names
+    assert "single_module.py" not in zip_names
+    assert "data_out.json" not in zip_names
+
+
+def test_build_src_package(fixture_project):
+    project = fixture_project("demo-src-package")
+    actions.do_build(project)
+
+    tar_names = get_tarball_names(project.root / "dist/demo-package-0.1.0.tar.gz")
+    assert "demo-package-0.1.0/src/my_package/__init__.py" in tar_names
+    assert "demo-package-0.1.0/src/my_package/data.json" in tar_names
+
+    zip_names = get_wheel_names(
+        project.root / "dist/demo_package-0.1.0-py3-none-any.whl"
+    )
+    assert "my_package/__init__.py" in zip_names
+    assert "my_package/data.json" in zip_names
+
+
+def test_build_package_include(fixture_project):
+    project = fixture_project("demo-package")
+    project.tool_settings["includes"] = [
+        "my_package/",
+        "single_module.py",
+        "data_out.json",
+    ]
+    project.tool_settings["excludes"] = ["my_package/*.json"]
+    project.write_pyproject()
+    actions.do_build(project)
+
+    tar_names = get_tarball_names(project.root / "dist/demo-package-0.1.0.tar.gz")
+    assert "demo-package-0.1.0/my_package/__init__.py" in tar_names
+    assert "demo-package-0.1.0/my_package/data.json" not in tar_names
+    assert "demo-package-0.1.0/single_module.py" in tar_names
+    assert "demo-package-0.1.0/data_out.json" in tar_names
+
+    zip_names = get_wheel_names(
+        project.root / "dist/demo_package-0.1.0-py3-none-any.whl"
+    )
+    assert "my_package/__init__.py" in zip_names
+    assert "my_package/data.json" not in zip_names
+    assert "single_module.py" in zip_names
+    assert "data_out.json" in zip_names
diff --git a/tests/conftest.py b/tests/conftest.py
index c4cbca192b57d64165da9c7412e3f39bf553059a..ea3078a245c5373cbcee81827d156f60c70a90d1 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -4,6 +4,7 @@ import json
 import os
 import shutil
 import sys
+from distutils.dir_util import copy_tree
 from io import BytesIO
 from pathlib import Path
 from typing import Callable, Iterable, List, Optional, Tuple
@@ -259,6 +260,18 @@ def project(project_no_init):
     return project_no_init
 
 
+@pytest.fixture()
+def fixture_project(project_no_init):
+    """Initailize a project from a fixture project"""
+
+    def func(project_name):
+        source = FIXTURES / "projects" / project_name
+        copy_tree(source.as_posix(), project_no_init.root.as_posix())
+        return project_no_init
+
+    return func
+
+
 @pytest.fixture()
 def repository(project, mocker):
     rv = TestRepository([], project.environment)
diff --git a/tests/fixtures/__init__.py b/tests/fixtures/__init__.py
new file mode 100644
index 0000000000000000000000000000000000000000..e69de29bb2d1d6434b8b29ae775ad8c2e48c5391
diff --git a/tests/fixtures/projects/__init__.py b/tests/fixtures/projects/__init__.py
new file mode 100644
index 0000000000000000000000000000000000000000..e69de29bb2d1d6434b8b29ae775ad8c2e48c5391
diff --git a/tests/fixtures/projects/demo-module/LICENSE b/tests/fixtures/projects/demo-module/LICENSE
new file mode 100644
index 0000000000000000000000000000000000000000..d1e1072ee5e1d109c15b6fd18756aedc2a401840
--- /dev/null
+++ b/tests/fixtures/projects/demo-module/LICENSE
@@ -0,0 +1 @@
+MIT License
diff --git a/tests/fixtures/projects/demo-module/README.md b/tests/fixtures/projects/demo-module/README.md
new file mode 100644
index 0000000000000000000000000000000000000000..b71cf80043e998e80c7d08b9e2abbf866db1ec74
--- /dev/null
+++ b/tests/fixtures/projects/demo-module/README.md
@@ -0,0 +1 @@
+# This is a demo module
diff --git a/tests/fixtures/projects/demo-module/bar_module.py b/tests/fixtures/projects/demo-module/bar_module.py
new file mode 100644
index 0000000000000000000000000000000000000000..c095cd59a2ee8a61e2d5603f8486b4e1928b78b0
--- /dev/null
+++ b/tests/fixtures/projects/demo-module/bar_module.py
@@ -0,0 +1 @@
+bar = "Hello"
diff --git a/tests/fixtures/projects/demo-module/foo_module.py b/tests/fixtures/projects/demo-module/foo_module.py
new file mode 100644
index 0000000000000000000000000000000000000000..1c7642a50c8188cf6ec01ec398ba5a281c4beba5
--- /dev/null
+++ b/tests/fixtures/projects/demo-module/foo_module.py
@@ -0,0 +1,2 @@
+__version__ = "0.1.0"
+foo = "hello"
diff --git a/tests/fixtures/projects/demo-module/pyproject.toml b/tests/fixtures/projects/demo-module/pyproject.toml
new file mode 100644
index 0000000000000000000000000000000000000000..c2c26e4be77be711aaddb9c5ef67914133987a10
--- /dev/null
+++ b/tests/fixtures/projects/demo-module/pyproject.toml
@@ -0,0 +1,17 @@
+[build-system]
+build-backend = "pdm.builders.api"
+requires = ["pdm"]
+
+[tool]
+[tool.pdm]
+author = "frostming <mianghong@gmail.com>"
+description = ""
+homepage = ""
+license = "MIT"
+name = "demo-module"
+python_requires = ">=3.5"
+version = { from = "foo_module.py" }
+
+[tool.pdm.dependencies]
+
+[tool.pdm.dev-dependencies]
diff --git a/tests/fixtures/projects/demo-package/LICENSE b/tests/fixtures/projects/demo-package/LICENSE
new file mode 100644
index 0000000000000000000000000000000000000000..d1e1072ee5e1d109c15b6fd18756aedc2a401840
--- /dev/null
+++ b/tests/fixtures/projects/demo-package/LICENSE
@@ -0,0 +1 @@
+MIT License
diff --git a/tests/fixtures/projects/demo-package/README.md b/tests/fixtures/projects/demo-package/README.md
new file mode 100644
index 0000000000000000000000000000000000000000..b71cf80043e998e80c7d08b9e2abbf866db1ec74
--- /dev/null
+++ b/tests/fixtures/projects/demo-package/README.md
@@ -0,0 +1 @@
+# This is a demo module
diff --git a/tests/fixtures/projects/demo-package/data_out.json b/tests/fixtures/projects/demo-package/data_out.json
new file mode 100644
index 0000000000000000000000000000000000000000..7c4c2f5ce2c6bab4bf622b4489306de7100142d9
--- /dev/null
+++ b/tests/fixtures/projects/demo-package/data_out.json
@@ -0,0 +1 @@
+{"name": "foo"}
diff --git a/tests/fixtures/projects/demo-package/my_package/__init__.py b/tests/fixtures/projects/demo-package/my_package/__init__.py
new file mode 100644
index 0000000000000000000000000000000000000000..3dc1f76bc69e3f559bee6253b24fc93acee9e1f9
--- /dev/null
+++ b/tests/fixtures/projects/demo-package/my_package/__init__.py
@@ -0,0 +1 @@
+__version__ = "0.1.0"
diff --git a/tests/fixtures/projects/demo-package/my_package/data.json b/tests/fixtures/projects/demo-package/my_package/data.json
new file mode 100644
index 0000000000000000000000000000000000000000..68372a39f38fbc281e4e5fea28de51ba4556904b
--- /dev/null
+++ b/tests/fixtures/projects/demo-package/my_package/data.json
@@ -0,0 +1 @@
+{"name": "demo-module"}
diff --git a/tests/fixtures/projects/demo-package/pyproject.toml b/tests/fixtures/projects/demo-package/pyproject.toml
new file mode 100644
index 0000000000000000000000000000000000000000..2afb228757df16ba3c2eb5c1448aa471e529ea86
--- /dev/null
+++ b/tests/fixtures/projects/demo-package/pyproject.toml
@@ -0,0 +1,18 @@
+[build-system]
+build-backend = "pdm.builders.api"
+requires = ["pdm"]
+
+[tool]
+[tool.pdm]
+author = "frostming <mianghong@gmail.com>"
+description = ""
+homepage = ""
+license = "MIT"
+name = "demo-package"
+python_requires = ">=3.5"
+version = { from = "my_package/__init__.py" }
+readme = "README.md"
+
+[tool.pdm.dependencies]
+
+[tool.pdm.dev-dependencies]
diff --git a/tests/fixtures/projects/demo-package/single_module.py b/tests/fixtures/projects/demo-package/single_module.py
new file mode 100644
index 0000000000000000000000000000000000000000..8cde7829c178ede96040e03f17c416d15bdacd01
--- /dev/null
+++ b/tests/fixtures/projects/demo-package/single_module.py
@@ -0,0 +1 @@
+print("hello world")
diff --git a/tests/fixtures/projects/demo-src-package/LICENSE b/tests/fixtures/projects/demo-src-package/LICENSE
new file mode 100644
index 0000000000000000000000000000000000000000..d1e1072ee5e1d109c15b6fd18756aedc2a401840
--- /dev/null
+++ b/tests/fixtures/projects/demo-src-package/LICENSE
@@ -0,0 +1 @@
+MIT License
diff --git a/tests/fixtures/projects/demo-src-package/README.md b/tests/fixtures/projects/demo-src-package/README.md
new file mode 100644
index 0000000000000000000000000000000000000000..b71cf80043e998e80c7d08b9e2abbf866db1ec74
--- /dev/null
+++ b/tests/fixtures/projects/demo-src-package/README.md
@@ -0,0 +1 @@
+# This is a demo module
diff --git a/tests/fixtures/projects/demo-src-package/__init__.py b/tests/fixtures/projects/demo-src-package/__init__.py
new file mode 100644
index 0000000000000000000000000000000000000000..e69de29bb2d1d6434b8b29ae775ad8c2e48c5391
diff --git a/tests/fixtures/projects/demo-src-package/data_out.json b/tests/fixtures/projects/demo-src-package/data_out.json
new file mode 100644
index 0000000000000000000000000000000000000000..7c4c2f5ce2c6bab4bf622b4489306de7100142d9
--- /dev/null
+++ b/tests/fixtures/projects/demo-src-package/data_out.json
@@ -0,0 +1 @@
+{"name": "foo"}
diff --git a/tests/fixtures/projects/demo-src-package/pyproject.toml b/tests/fixtures/projects/demo-src-package/pyproject.toml
new file mode 100644
index 0000000000000000000000000000000000000000..02343c38cd218bd4a43a54983f32840dac7f346b
--- /dev/null
+++ b/tests/fixtures/projects/demo-src-package/pyproject.toml
@@ -0,0 +1,17 @@
+[build-system]
+build-backend = "pdm.builders.api"
+requires = ["pdm"]
+
+[tool]
+[tool.pdm]
+author = "frostming <mianghong@gmail.com>"
+description = ""
+homepage = ""
+license = "MIT"
+name = "demo-package"
+python_requires = ">=3.5"
+version = { from = "src/my_package/__init__.py" }
+
+[tool.pdm.dependencies]
+
+[tool.pdm.dev-dependencies]
diff --git a/tests/fixtures/projects/demo-src-package/single_module.py b/tests/fixtures/projects/demo-src-package/single_module.py
new file mode 100644
index 0000000000000000000000000000000000000000..8cde7829c178ede96040e03f17c416d15bdacd01
--- /dev/null
+++ b/tests/fixtures/projects/demo-src-package/single_module.py
@@ -0,0 +1 @@
+print("hello world")
diff --git a/tests/fixtures/projects/demo-src-package/src/__init__.py b/tests/fixtures/projects/demo-src-package/src/__init__.py
new file mode 100644
index 0000000000000000000000000000000000000000..e69de29bb2d1d6434b8b29ae775ad8c2e48c5391
diff --git a/tests/fixtures/projects/demo-src-package/src/my_package/__init__.py b/tests/fixtures/projects/demo-src-package/src/my_package/__init__.py
new file mode 100644
index 0000000000000000000000000000000000000000..3dc1f76bc69e3f559bee6253b24fc93acee9e1f9
--- /dev/null
+++ b/tests/fixtures/projects/demo-src-package/src/my_package/__init__.py
@@ -0,0 +1 @@
+__version__ = "0.1.0"
diff --git a/tests/fixtures/projects/demo-src-package/src/my_package/data.json b/tests/fixtures/projects/demo-src-package/src/my_package/data.json
new file mode 100644
index 0000000000000000000000000000000000000000..68372a39f38fbc281e4e5fea28de51ba4556904b
--- /dev/null
+++ b/tests/fixtures/projects/demo-src-package/src/my_package/data.json
@@ -0,0 +1 @@
+{"name": "demo-module"}
diff --git a/tests/fixtures/projects/test-plugin-pdm/setup.py b/tests/fixtures/projects/test-plugin-pdm/setup.py
deleted file mode 100644
index 6228f4e99d909cacbd0d1488fabd938596ede2ca..0000000000000000000000000000000000000000
--- a/tests/fixtures/projects/test-plugin-pdm/setup.py
+++ /dev/null
@@ -1,9 +0,0 @@
-from setuptools import setup
-
-
-setup(
-    name="test-plugin",
-    version="0.0.1",
-    py_modules=["hello"],
-    entry_points={"pdm.plugin": ["hello = hello:main"]},
-)