diff --git a/tests/Phing/Test/Task/System/ReplaceRegexpTaskTest.php b/tests/Phing/Test/Task/System/ReplaceRegexpTaskTest.php
index 82eb1f75d..18da8aca0 100644
--- a/tests/Phing/Test/Task/System/ReplaceRegexpTaskTest.php
+++ b/tests/Phing/Test/Task/System/ReplaceRegexpTaskTest.php
@@ -59,4 +59,10 @@ public function testFailOnError(): void
             "Error reading file:"
         );
     }
+
+    public function testFlags(): void
+    {
+        $this->executeTarget(__FUNCTION__);
+        $this->assertStringEqualsFile('test.properties', 'NewProperty=12345');
+    }
 }