diff --git a/add_links/match.py b/add_links/match.py
index a3440e7..732e3ba 100644
--- a/add_links/match.py
+++ b/add_links/match.py
@@ -205,7 +205,11 @@ def match_found(m: re.Match[str], q: str, linkto: str | None) -> str:
         if pos == 0 or m.string[pos - 1] == "\n":
             replacement = replacement[0].upper() + replacement[1:]
     if linkto:
-        if linkto[0].isupper() and replacement[0] == linkto[0].lower():
+        if (
+            linkto[0].isupper()
+            and replacement[0].islower()
+            and not is_title_case(replacement)
+        ):
             linkto = linkto[0].lower() + linkto[1:]
         elif replacement[0].isupper():
             linkto = linkto[0].upper() + linkto[1:]
diff --git a/test_match.py b/test_match.py
new file mode 100644
index 0000000..c50470e
--- /dev/null
+++ b/test_match.py
@@ -0,0 +1,75 @@
+import unittest
+
+from add_links.match import NoMatch, find_link_in_content
+
+
+class FindLinkInContentTests(unittest.TestCase):
+    def test_links_first_of_two_adjacent_existing_links(self) -> None:
+        content = (
+            "'''''North Star''''' is a 1974 British [[thriller novel]] by "
+            "[[Hammond Innes]].<ref>Vinson & Kirkpatrick p.455</ref> "
+            "A man tries to prevent a plot to blow up a [[North Sea]] [[oil rig]]."
+        )
+
+        new_content, replacement, replaced_text = find_link_in_content(
+            "North Sea oil", content
+        )
+
+        self.assertEqual(
+            new_content,
+            "'''''North Star''''' is a 1974 British [[thriller novel]] by "
+            "[[Hammond Innes]].<ref>Vinson & Kirkpatrick p.455</ref> "
+            "A man tries to prevent a plot to blow up a "
+            "[[North Sea oil|North Sea]] [[oil rig]].",
+        )
+        self.assertEqual(replacement, "North Sea oil")
+        self.assertEqual(replaced_text, "North Sea]] [[oil")
+
+    def test_merges_existing_link_with_following_plain_text(self) -> None:
+        content = "[[anti-globalization]] movement"
+
+        new_content, replacement, replaced_text = find_link_in_content(
+            "anti-globalization movement", content
+        )
+
+        self.assertEqual(new_content, "[[anti-globalization movement]]")
+        self.assertEqual(replacement, "anti-globalization movement")
+        self.assertEqual(replaced_text, "anti-globalization]] movement")
+
+    def test_links_prefix_before_existing_link(self) -> None:
+        content = "cross-platform [[interchange station]]"
+
+        new_content, replacement, replaced_text = find_link_in_content(
+            "cross-platform interchange", content
+        )
+
+        self.assertEqual(
+            new_content,
+            "[[cross-platform interchange|cross-platform]] [[interchange station]]",
+        )
+        self.assertEqual(replacement, "cross-platform interchange")
+        self.assertEqual(replaced_text, "cross-platform [[interchange")
+
+    def test_lowercases_redirect_target_for_sentence_case_display_text(self) -> None:
+        content = (
+            "The absence of a voters' roll requirement was controversial, with "
+            "the NCA alleging potential rigging through ballot stuffing and "
+            "coercion in rural areas."
+        )
+
+        new_content, replacement, replaced_text = find_link_in_content(
+            "ballot stuffing", content, "Electoral fraud"
+        )
+
+        self.assertEqual(
+            new_content,
+            "The absence of a voters' roll requirement was controversial, with "
+            "the NCA alleging potential rigging through "
+            "[[electoral fraud|ballot stuffing]] and coercion in rural areas.",
+        )
+        self.assertEqual(replacement, "electoral fraud|ballot stuffing")
+        self.assertEqual(replaced_text, "ballot stuffing")
+
+
+if __name__ == "__main__":
+    unittest.main()