diff --git a/AUTHORS.rst b/AUTHORS.rst
index 90401390..23819dd3 100644
--- a/AUTHORS.rst
+++ b/AUTHORS.rst
@@ -63,4 +63,5 @@ Patches and suggestions
 - Ville Skyttä
 - Hugo van Kemenade
 - Mark Vasilkov
+- fly1d
 
diff --git a/CHANGES.rst b/CHANGES.rst
index 47dcda3a..762f6b74 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -18,6 +18,7 @@ Features:
 
 Bug fixes:
 
+* Keep cached tree builder modules when another configuration is requested. (#585)
 * The sanitizer now permits ``<summary>`` tags. It used to allow ``<details>``
   already. (#423)
 
diff --git a/html5lib/_utils.py b/html5lib/_utils.py
index 7e23ee57..346783c8 100644
--- a/html5lib/_utils.py
+++ b/html5lib/_utils.py
@@ -135,12 +135,10 @@ def moduleFactory(baseModule, *args, **kwargs):
             mod = ModuleType(name)
             objs = factory(baseModule, *args, **kwargs)
             mod.__dict__.update(objs)
-            if "name" not in moduleCache:
+            if name not in moduleCache:
                 moduleCache[name] = {}
-            if "args" not in moduleCache[name]:
+            if args not in moduleCache[name]:
                 moduleCache[name][args] = {}
-            if "kwargs" not in moduleCache[name][args]:
-                moduleCache[name][args][kwargs_tuple] = {}
             moduleCache[name][args][kwargs_tuple] = mod
             return mod
 
diff --git a/html5lib/tests/test_module_factory.py b/html5lib/tests/test_module_factory.py
new file mode 100644
index 00000000..f02caaf5
--- /dev/null
+++ b/html5lib/tests/test_module_factory.py
@@ -0,0 +1,87 @@
+from __future__ import absolute_import, division, unicode_literals
+
+from types import ModuleType
+import xml.etree.ElementTree as ElementTree
+
+import pytest
+
+from html5lib import HTMLParser, getTreeBuilder
+from html5lib._utils import moduleFactoryFactory
+
+
+def _module_factory():
+    def factory(backend, *args, **kwargs):
+        return {"backend": backend, "arguments": args, "options": kwargs}
+
+    return moduleFactoryFactory(factory)
+
+
+@pytest.mark.parametrize("args_a, options_a, args_b, options_b", [
+    (("first",), {}, ("second",), {}),
+    ((), {"enabled": False}, (), {"enabled": True}),
+    (("first",), {"enabled": False}, ("first",), {"enabled": True}),
+    (("first",), {"enabled": False}, ("second",), {"enabled": False}),
+], ids=["positional", "keyword", "shared-arguments", "shared-options"])
+def test_module_factory_reuses_each_configuration(args_a, options_a, args_b, options_b):
+    backend = ModuleType(str("factory_backend"))
+    build = _module_factory()
+
+    first = build(backend, *args_a, **options_a)
+    second = build(backend, *args_b, **options_b)
+    first_again = build(backend, *args_a, **options_a)
+    second_again = build(backend, *args_b, **options_b)
+
+    assert first.backend is backend
+    assert second.backend is backend
+    assert first.arguments == args_a
+    assert second.arguments == args_b
+    assert first.options == options_a
+    assert second.options == options_b
+    assert first_again.arguments == args_a
+    assert first_again.options == options_a
+    assert second_again.arguments == args_b
+    assert second_again.options == options_b
+    assert first is not second
+    assert first_again is first
+    assert second_again is second
+
+
+def test_module_factory_keeps_distinct_backends_cached():
+    backend_a = ModuleType(str("factory_backend_a"))
+    backend_b = ModuleType(str("factory_backend_b"))
+    build = _module_factory()
+
+    first = build(backend_a, enabled=True)
+    second = build(backend_b, enabled=True)
+
+    assert first.backend is backend_a
+    assert second.backend is backend_b
+    assert first is not second
+    assert build(backend_a, enabled=True) is first
+    assert build(backend_b, enabled=True) is second
+
+
+@pytest.mark.parametrize("full_tree", [False, True])
+def test_etree_builder_identity_survives_alternating_options(full_tree):
+    first = getTreeBuilder("etree", ElementTree, fullTree=full_tree)
+    first_parser = HTMLParser(tree=first, namespaceHTMLElements=False)
+    second = getTreeBuilder("etree", ElementTree, fullTree=not full_tree)
+    second_parser = HTMLParser(tree=second, namespaceHTMLElements=False)
+    first_again = getTreeBuilder("etree", ElementTree, fullTree=full_tree)
+    second_again = getTreeBuilder("etree", ElementTree, fullTree=not full_tree)
+
+    assert first.implementation is ElementTree
+    assert second.implementation is ElementTree
+    assert first is not second
+    assert first_again is first
+    assert second_again is second
+    assert isinstance(first_parser.tree, first_again)
+    assert isinstance(second_parser.tree, second_again)
+
+    # Parsing is an existing-behavior control, not the cache regression itself.
+    parsers = [(first_parser, full_tree), (second_parser, not full_tree)]
+    for parser, includes_document in parsers:
+        document = parser.parse("<p>content</p>")
+        root = document.find("html") if includes_document else document
+        assert root.tag == "html"
+        assert root.find("body/p").text == "content"