diff --git a/tika-core/src/test/java/org/apache/tika/digest/InputStreamDigesterTest.java b/tika-core/src/test/java/org/apache/tika/digest/InputStreamDigesterTest.java
new file mode 100644
index 0000000000..34b2d28954
--- /dev/null
+++ b/tika-core/src/test/java/org/apache/tika/digest/InputStreamDigesterTest.java
@@ -0,0 +1,46 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.tika.digest;
+
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+
+import java.nio.charset.StandardCharsets;
+import java.util.Base64;
+
+import org.junit.jupiter.api.Test;
+
+import org.apache.tika.io.TikaInputStream;
+import org.apache.tika.metadata.Metadata;
+import org.apache.tika.metadata.Property;
+import org.apache.tika.parser.ParseContext;
+
+public class InputStreamDigesterTest {
+
+    @Test
+    public void testReservedDigestKeySurvivesGuard() throws Exception {
+        String key = "X-TIKA:digest:SHA256";
+        InputStreamDigester digester = new InputStreamDigester("SHA256", key,
+                bytes -> Base64.getEncoder().encodeToString(bytes));
+        Metadata metadata = new Metadata();
+        try (TikaInputStream tis =
+                     TikaInputStream.get("hello world".getBytes(StandardCharsets.UTF_8))) {
+            digester.digest(tis, metadata, new ParseContext());
+        }
+        assertNotNull(metadata.get(key), "trusted digest write must survive the reserved-key guard");
+        assertNotNull(Property.get(key), "digest key must be registered as a Property");
+    }
+}