diff --git a/lib/spack/spack/package_base.py b/lib/spack/spack/package_base.py
index 54ba4bac32e..cf2ca6c8de6 100644
--- a/lib/spack/spack/package_base.py
+++ b/lib/spack/spack/package_base.py
@@ -850,15 +850,9 @@ def fullnames(cls):
 
     @classproperty
     def name(cls):
-        """The name of this package.
-
-        The name of a package is the name of its Python module, without
-        the containing module names.
-        """
+        """The canonical name of this package"""
         if cls._name is None:
-            cls._name = cls.module.__name__
-            if "." in cls._name:
-                cls._name = cls._name[cls._name.rindex(".") + 1 :]
+            cls._name = spack.repo.pkg_name_from_module(cls.__module__)
         return cls._name
 
     @classproperty
diff --git a/lib/spack/spack/repo.py b/lib/spack/spack/repo.py
index 2e1b613bd00..3b8427442da 100644
--- a/lib/spack/spack/repo.py
+++ b/lib/spack/spack/repo.py
@@ -83,6 +83,21 @@ def namespace_from_fullname(fullname):
     return namespace
 
 
+def pkg_name_from_module(module_name: str) -> str:
+    """Return the actual package name from a module name.
+
+    For instance ``spack.pkg.builtin.num3dtk`` has package name ``3dtk``
+    and ``spack.pkg.builtin.py_numpy`` has package name ``py-numpy``
+    """
+    if not module_name.startswith(f"{ROOT_PYTHON_NAMESPACE}."):
+        raise ValueError(f"Module '{module_name}' is not a Spack package module")
+    namespace, _, import_name = module_name[len(ROOT_PYTHON_NAMESPACE) + 1 :].rpartition(".")
+    name = PATH.get_repo(namespace).real_name(import_name)
+    if name is None:
+        raise ValueError(f"Module '{module_name}' does not correspond to a known package")
+    return name
+
+
 class SpackNamespaceLoader:
     def create_module(self, spec):
         return SpackNamespace(spec.name)
diff --git a/lib/spack/spack/test/packages.py b/lib/spack/spack/test/packages.py
index 2912c689079..50192f86b6b 100644
--- a/lib/spack/spack/test/packages.py
+++ b/lib/spack/spack/test/packages.py
@@ -2,6 +2,7 @@
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 
+import importlib
 import os
 
 import pytest
@@ -333,3 +334,8 @@ def test_package_can_have_sparse_checkout_properties(mock_packages, mock_fetch,
     assert isinstance(fetcher, spack.fetch_strategy.GitFetchStrategy)
     assert hasattr(fetcher, "git_sparse_paths")
     assert fetcher.git_sparse_paths == pkg_cls.git_sparse_paths
+
+
+def test_package_name_from_class_type(mock_packages):
+    module = importlib.import_module("spack.pkg.builtin.mock.num7zip")
+    assert module._7zip.name == "7zip"