diff --git a/tests/src/unit-user_defined_input.cpp b/tests/src/unit-user_defined_input.cpp
index 7c6d5b746..0884b193d 100644
--- a/tests/src/unit-user_defined_input.cpp
+++ b/tests/src/unit-user_defined_input.cpp
@@ -173,16 +173,13 @@ struct CustomSentinel
 {
     const char* end_ptr;
 
-    // Support both directions for != comparison
+    // only the iterator-first direction (it != sentinel) is ever evaluated by
+    // the library's parse loop; a reversed-order overload would go unused and
+    // trip -Wunneeded-internal-declaration under -Weverything
     friend bool operator!=(const char* it, const CustomSentinel& sentinel)
     {
         return it != sentinel.end_ptr;
     }
-
-    friend bool operator!=(const CustomSentinel& sentinel, const char* it)
-    {
-        return it != sentinel.end_ptr;
-    }
 };
 
 TEST_CASE("Parse with heterogeneous iterator and sentinel types")