diff --git a/plugin/src/main/java/de/ids_mannheim/korap/plkexport/IdsExportService.java b/plugin/src/main/java/de/ids_mannheim/korap/plkexport/IdsExportService.java
index 4e2968e..bd715e0 100644
--- a/plugin/src/main/java/de/ids_mannheim/korap/plkexport/IdsExportService.java
+++ b/plugin/src/main/java/de/ids_mannheim/korap/plkexport/IdsExportService.java
@@ -231,7 +231,6 @@
         if (format.equals("json")) {
             builder = Response.ok(resp);
             builder.type(MediaType.APPLICATION_JSON);
-            fname = fname + ".json";
         }
 
         // format == rtf / else
@@ -255,11 +254,16 @@
 
             String rtfresp = writeRTF(listMatches);
             builder = Response.ok(rtfresp);
-            fname = fname + ".rtf";
+            format = "rtf";
         }
 
-        builder.header("Content-Disposition",
-                       "attachment; filename=" + sanitizeFileName(fname));
+        builder.header(
+            "Content-Disposition",
+            "attachment; filename=" +
+            sanitizeFileName(fname) +
+            '.' +
+            format
+            );
         Response response = builder.build();
         return response;
     }
diff --git a/plugin/src/test/java/de/ids_mannheim/korap/plkexport/IdsExportServiceTest.java b/plugin/src/test/java/de/ids_mannheim/korap/plkexport/IdsExportServiceTest.java
index 26698d2..0761da7 100644
--- a/plugin/src/test/java/de/ids_mannheim/korap/plkexport/IdsExportServiceTest.java
+++ b/plugin/src/test/java/de/ids_mannheim/korap/plkexport/IdsExportServiceTest.java
@@ -130,7 +130,7 @@
         // The document should be named correctly
         assertTrue("Request JSON: Filename should be set correctly: ",
                    responsejson.getHeaderString(HttpHeaders.CONTENT_DISPOSITION)
-                   .contains("filename=" + filenamej));
+                   .contains("filename=" + filenamej + ".json"));
 
         frmap.remove("ql");
         responsejson = target("/export").request()
@@ -264,7 +264,7 @@
         // The document should be named correctly
         assertTrue("Request RTF: Filename should be set correctly: ",
                 responsertf.getHeaderString(HttpHeaders.CONTENT_DISPOSITION)
-                        .contains("filename=" + filenamer));
+                        .contains("filename=" + filenamer + ".rtf"));
 
         Response resp;
         String fvalue;