diff --git a/Tests/SwiftParserTest/AttributeTests.swift b/Tests/SwiftParserTest/AttributeTests.swift
index 9ee34b05332..98cadfc7318 100644
--- a/Tests/SwiftParserTest/AttributeTests.swift
+++ b/Tests/SwiftParserTest/AttributeTests.swift
@@ -579,6 +579,12 @@ final class AttributeTests: ParserTestCase {
       """
     )
 
+    assertParse(
+      """
+      @_expose(!Cxx) func foo() {}
+      """
+    )
+
     assertParse(
       """
       @_expose(Cxx, "baz") func foo() {}