diff --git a/plugins/mapper-attachments/src/test/java/org/elasticsearch/mapper/attachments/MultifieldAttachmentMapperTests.java b/plugins/mapper-attachments/src/test/java/org/elasticsearch/mapper/attachments/MultifieldAttachmentMapperTests.java
index 6b781a6f4a6..5459bc6aef8 100644
--- a/plugins/mapper-attachments/src/test/java/org/elasticsearch/mapper/attachments/MultifieldAttachmentMapperTests.java
+++ b/plugins/mapper-attachments/src/test/java/org/elasticsearch/mapper/attachments/MultifieldAttachmentMapperTests.java
@@ -153,4 +153,45 @@ public class MultifieldAttachmentMapperTests extends AttachmentUnitTestCase {
         // In mapping we set store:true for suggest subfield
         assertThat(doc.rootDoc().getField("file.name.suggest").fieldType().stored(), is(true));
     }
+
+    public void testAllExternalValues() throws Exception {
+        String originalText = "This is an elasticsearch mapper attachment test.";
+        String forcedName = randomAsciiOfLength(20);
+        String forcedLanguage = randomAsciiOfLength(20);
+        String forcedContentType = randomAsciiOfLength(20);
+
+        String bytes = Base64.encodeBytes(originalText.getBytes(StandardCharsets.ISO_8859_1));
+        threadPool = new ThreadPool("testing-only");
+
+        MapperService mapperService = MapperTestUtils.newMapperService(createTempDir(),
+            Settings.builder().put(AttachmentMapper.INDEX_ATTACHMENT_DETECT_LANGUAGE_SETTING.getKey(), true).build(),
+            getIndicesModuleWithRegisteredAttachmentMapper());
+
+        String mapping = copyToStringFromClasspath("/org/elasticsearch/index/mapper/attachment/test/unit/multifield/multifield-mapping.json");
+
+        DocumentMapper documentMapper = mapperService.documentMapperParser().parse("person", new CompressedXContent(mapping));
+
+        ParsedDocument doc = documentMapper.parse("person", "person", "1", XContentFactory.jsonBuilder()
+                .startObject()
+                    .startObject("file")
+                        .field("_content", bytes)
+                        .field("_name", forcedName)
+                        .field("_language", forcedLanguage)
+                        .field("_content_type", forcedContentType)
+                    .endObject()
+                .endObject()
+                .bytes());
+
+        // Note that we don't support forcing values for _title and _keywords
+
+        assertThat(doc.rootDoc().getField("file.content"), notNullValue());
+        assertThat(doc.rootDoc().getField("file.content").stringValue(), is(originalText + "\n"));
+
+        assertThat(doc.rootDoc().getField("file.name"), notNullValue());
+        assertThat(doc.rootDoc().getField("file.name").stringValue(), is(forcedName));
+        assertThat(doc.rootDoc().getField("file.language"), notNullValue());
+        assertThat(doc.rootDoc().getField("file.language").stringValue(), is(forcedLanguage));
+        assertThat(doc.rootDoc().getField("file.content_type"), notNullValue());
+        assertThat(doc.rootDoc().getField("file.content_type").stringValue(), is(forcedContentType));
+    }
 }