diff -r 3216733e3ad4 third_party/python/moz.l10n/moz/l10n/paths/config.py
--- a/third_party/python/moz.l10n/moz/l10n/paths/config.py
+++ b/third_party/python/moz.l10n/moz/l10n/paths/config.py
@@ -134,7 +134,7 @@
                         f"Wildcard mismatch between reference & l10n: {path}"
                     )
                 ref_re = compile(
-                    path_stars.sub("(.*)", ref.replace(sep, "/").replace(".", r"\."))
+                    path_stars.sub("(.*)", ref.replace(sep, "/").replace(".", r"\.").replace("+", r"\+"))
                 )
                 *tgt_parts, tgt_end = path_stars.split(target)