diff --git a/HISTORY.rst b/HISTORY.rst
index 87c7465..c57871d 100644
--- a/HISTORY.rst
+++ b/HISTORY.rst
@@ -1,6 +1,13 @@
 History
 =======
 
+Pending
+-------
+
+* Fix URL parameter encoding - URL escaping like `%3A` will now be passed
+  correctly to your application
+  (`Issue #101 <https://github.com/adamchainz/apig-wsgi/issues/101>`__).
+
 2.4.0 (2019-11-15)
 ------------------
 
diff --git a/tests/test_apig_wsgi.py b/tests/test_apig_wsgi.py
index f6b77e9..dd596ab 100644
--- a/tests/test_apig_wsgi.py
+++ b/tests/test_apig_wsgi.py
@@ -241,6 +241,22 @@ def test_querystring_one(simple_app):
     assert simple_app.environ["QUERY_STRING"] == "foo=bar"
 
 
+def test_querystring_encoding_value(simple_app):
+    event = make_event(qs_params={"foo": "a%20bar"})
+
+    simple_app.handler(event, None)
+
+    assert simple_app.environ["QUERY_STRING"] == "foo=a%20bar"
+
+
+def test_querystring_encoding_key(simple_app):
+    event = make_event(qs_params={"a%20foo": "bar"})
+
+    simple_app.handler(event, None)
+
+    assert simple_app.environ["QUERY_STRING"] == "a%20foo=bar"
+
+
 def test_plain_header(simple_app):
     event = make_event(headers={"Test-Header": "foobar"})