diff --git a/pageviewapi/client.py b/pageviewapi/client.py
index e55c852..589e734 100644
--- a/pageviewapi/client.py
+++ b/pageviewapi/client.py
@@ -11,6 +11,7 @@
 
 from importlib.metadata import PackageNotFoundError, version
 from typing import Any
+from urllib.parse import quote, unquote
 
 import requests
 
@@ -100,7 +101,7 @@ def per_article(
     """
     args = PA_ARGS.format(
         project=project,
-        page=page,
+        page=_quote_article_name(page),
         start=start,
         end=end,
         access=access,
@@ -199,3 +200,7 @@ def _api(end_point: str, args: str, api_url: str = API_BASE_URL) -> dict[str, An
     else:
         response.raise_for_status()
         return {}  # unreachable, satisfies type checker
+
+
+def _quote_article_name(page: str) -> str:
+    return quote(unquote(page), safe="")
diff --git a/tests/test_client.py b/tests/test_client.py
index 5d4271d..d0b431b 100644
--- a/tests/test_client.py
+++ b/tests/test_client.py
@@ -11,6 +11,7 @@
     ThrottlingException,
     ZeroOrDataNotLoadedException,
     _api,
+    _quote_article_name,
     aggregate,
     legacy_pagecounts,
     per_article,
@@ -209,3 +210,26 @@ def test_api_returns_pageview_response(ok_response):
     with patch("requests.get", return_value=ok_response):
         result = per_article("en.wikipedia", "Paris", "20151106", "20151120")
     assert isinstance(result, PageviewResponse)
+
+
+def test_quote_article_name_plain():
+    assert _quote_article_name("Paris") == "Paris"
+
+
+def test_quote_article_name_slash():
+    assert _quote_article_name("AC/DC") == "AC%2FDC"
+
+
+def test_per_article_encodes_space_in_page_name(ok_response):
+    with patch("requests.get", return_value=ok_response) as mock_get:
+        per_article("en.wikipedia", "New York", "20200101", "20200131")
+    url = mock_get.call_args[0][0]
+    assert "New%20York" in url
+    assert "New York" not in url
+
+
+def test_per_article_encodes_slash_in_page_name(ok_response):
+    with patch("requests.get", return_value=ok_response) as mock_get:
+        per_article("en.wikipedia", "AC/DC", "20200101", "20200131")
+    url = mock_get.call_args[0][0]
+    assert "AC%2FDC" in url