diff --git a/tests/test_interpolation.py b/tests/test_interpolation.py
index e891cb3d8..d748e4325 100644
--- a/tests/test_interpolation.py
+++ b/tests/test_interpolation.py
@@ -795,7 +795,7 @@ def _maybe_create(definition: str) -> Any:
     ("str_quoted_too_many_2", "${test:'a''}", GrammarParseError),
     ("str_quoted_too_many_3", "${test:''a''}", GrammarParseError),
     # Unquoted strings (within interpolations).
-    ("str_legal", "${test:a/-\\+.$*, \\\\}", ["a/-\\+.$*", "\\"]),
+    ("str_legal", "${test:a/-\\+.$*@, \\\\}", ["a/-\\+.$*@", "\\"]),
     ("str_illegal_1", "${test:a,=b}", GrammarParseError),
     ("str_illegal_2", f"${{test:{chr(200)}}}", GrammarParseError),
     ("str_illegal_3", f"${{test:{chr(129299)}}}", GrammarParseError),