diff --git a/src/main/java/info/peper/vz/rest/VzRestController.java b/src/main/java/info/peper/vz/rest/VzRestController.java
index f42d716..f4ea621 100644
--- a/src/main/java/info/peper/vz/rest/VzRestController.java
+++ b/src/main/java/info/peper/vz/rest/VzRestController.java
@@ -70,7 +70,7 @@ class VzRestController {
 		return prices;
 	}
 	
-	@GetMapping("/data/summary")
+	@GetMapping(value="/data/summary", produces = {"text/plain"})
 	String getSummary2(@RequestParam(name = "timestampStart", defaultValue = "-1")long timestampStart,
 			@RequestParam(name = "timestampEnd", defaultValue = "-1")long timestampEnd,
 			@RequestParam(name = "duration", defaultValue = "")final String duration,