diff --git a/tests/test_convert_salary_excel.py b/tests/test_convert_salary_excel.py
index 7726f22..8631b15 100644
--- a/tests/test_convert_salary_excel.py
+++ b/tests/test_convert_salary_excel.py
@@ -1,7 +1,12 @@
 import unittest
 from types import SimpleNamespace
 
-from tools.convert_salary_excel import detect_column_type, parse_sheet
+from tools.convert_salary_excel import (
+    INDEX_PATTERNS,
+    detect_column_type,
+    header_matches,
+    parse_sheet,
+)
 
 
 class FakeWorksheet:
@@ -44,6 +49,14 @@ class DetectColumnTypeTests(unittest.TestCase):
     def test_danish_compound_headers_still_match(self):
         self.assertEqual(detect_column_type("Lønindeks"), "index")
 
+    def test_compound_patterns_match_as_substring_but_others_do_not(self):
+        # A compound token (Danish "løn") matches inside a glued header word.
+        self.assertTrue(header_matches("lønindeks", INDEX_PATTERNS))
+        # A pattern that is not a compound token ("salary") only matches as a
+        # whole token, so it must not match inside an unrelated glued word.
+        self.assertFalse(header_matches("salaryindex", INDEX_PATTERNS))
+        self.assertTrue(header_matches("salary index", INDEX_PATTERNS))
+
     def test_parse_sheet_preserves_category_name_with_letter_n(self):
         ws = FakeWorksheet([
             ("Company", "Engineering Count", "Engineering Index"),
diff --git a/tools/convert_salary_excel.py b/tools/convert_salary_excel.py
index 8b26ff5..512bf15 100644
--- a/tools/convert_salary_excel.py
+++ b/tools/convert_salary_excel.py
@@ -42,18 +42,28 @@ COMPANY_PATTERNS = {"firma", "company", "virksomhed", "employer", "arbejdsgiver"
 CITY_PATTERNS = {"by", "city", "kommune", "location", "lokation", "sted"}
 COUNT_PATTERNS = {"antal", "count", "number", "n", "employees", "medarbejdere"}
 INDEX_PATTERNS = {"indeks", "index", "idx", "salary", "løn", "median", "average", "gennemsnit"}
-DANISH_COMPOUND_PATTERNS = {"antal", "indeks", "løn", "gennemsnit", "medarbejdere"}
+# "Compound" tokens: pattern words allowed to match as a substring of a larger
+# header token, for languages that glue words together (e.g. Danish "lønindeks"
+# -> løn + indeks). Languages that write headers as separate words need none.
+# Ships populated for this repo's Danish demonstration data; a fork targeting
+# another locale edits this constant.
+COMPOUND_PATTERNS = {"antal", "indeks", "løn", "gennemsnit", "medarbejdere"}
 
 
 def header_matches(header, patterns):
-    """Return True when a header contains a meaningful pattern match."""
+    """Return True when a header contains a meaningful pattern match.
+
+    Patterns match whole tokens; any pattern also listed in
+    ``COMPOUND_PATTERNS`` may additionally match as a substring, to handle
+    languages that form compound words.
+    """
     h = header.lower().strip()
     tokens = set(re.findall(r"[a-zæøåöäü0-9]+", h))
 
     for p in patterns:
         if p in tokens:
             return True
-        if p in DANISH_COMPOUND_PATTERNS and p in h:
+        if p in COMPOUND_PATTERNS and p in h:
             return True
     return False