diff --git a/conservancy_beancount/rtutil.py b/conservancy_beancount/rtutil.py
index 081d7f1bf2f8a100c7a5a35ac43f23c5f6ab362a..f1548456fae820629b46285a4586344d7dbb08db 100644
--- a/conservancy_beancount/rtutil.py
+++ b/conservancy_beancount/rtutil.py
@@ -50,7 +50,7 @@ class RT:
         self.rt = rt_client
         urlparts = urlparse.urlparse(rt_client.url)
         try:
-            index = urlparts.path.index('/REST/')
+            index = urlparts.path.rindex('/REST/')
         except ValueError:
             base_path = urlparts.path.rstrip('/') + '/'
         else:
diff --git a/tests/test_rtutil.py b/tests/test_rtutil.py
index 87333e7c54704b85879d570762266731466e2876..9aed048bbc91874b0513f51f1964958c78f38a5f 100644
--- a/tests/test_rtutil.py
+++ b/tests/test_rtutil.py
@@ -121,3 +121,9 @@ def test_exists_caches(new_client):
 ])
 def test_parse(rt, link, expected):
     assert rt.parse(link) == expected
+
+def test_uncommon_server_url_parsing():
+    url = 'https://example.org/REST/1.0/'
+    client = testutil.RTClient(url + 'REST/1.0/')
+    rt = rtutil.RT(client)
+    assert rt.url(1).startswith(url)