diff --git a/docs/source/about/changelog.rst b/docs/source/about/changelog.rst
index 2a48d6f37..0a6117b8b 100644
--- a/docs/source/about/changelog.rst
+++ b/docs/source/about/changelog.rst
@@ -23,7 +23,11 @@ more info, see the :ref:`Contributor Guide <Creating a Changelog Entry>`.
 Unreleased
 ----------
 
-No changes.
+**Fixed**
+
+- :pull:`911` - fixed ``data-*`` and ``aria-*`` attribute name conversions. Previously
+  an attribute declared as ``data_some_thing`` got converted to ``data-some_thing``
+  instead of ``data-some-thing``.
 
 
 v1.0.0-a3
diff --git a/src/client/packages/idom-client-react/src/element-utils.js b/src/client/packages/idom-client-react/src/element-utils.js
index 334ca9019..a3ec61c3e 100644
--- a/src/client/packages/idom-client-react/src/element-utils.js
+++ b/src/client/packages/idom-client-react/src/element-utils.js
@@ -64,7 +64,7 @@ function normalizeAttribute([key, value]) {
     key.startsWith("aria_") ||
     DASHED_HTML_ATTRS.includes(key)
   ) {
-    normKey = key.replace("_", "-");
+    normKey = key.split("_").join("-");
   } else {
     normKey = snakeToCamel(key);
   }
diff --git a/tests/test_client.py b/tests/test_client.py
index fae191078..c833d1bbf 100644
--- a/tests/test_client.py
+++ b/tests/test_client.py
@@ -132,3 +132,23 @@ async def handle_change(event):
     await inp.type("hello", delay=DEFAULT_TYPE_DELAY)
 
     assert (await inp.evaluate("node => node.value")) == "hello"
+
+
+async def test_data_and_aria_attribute_naming(display: DisplayFixture):
+    @idom.component
+    def SomeComponent():
+        return idom.html.h1(
+            "see attributes",
+            id="title",
+            data_some_thing="some data",
+            aria_description="some title",
+            **{"data-another-thing": "more data"},
+        )
+
+    await display.show(SomeComponent)
+
+    title = await display.page.wait_for_selector("#title")
+
+    assert await title.get_attribute("data-some-thing") == "some data"
+    assert await title.get_attribute("data-another-thing") == "more data"
+    assert await title.get_attribute("aria-description") == "some title"