diff --git a/Changes b/Changes
index c503c38..c0dd87a 100644
--- a/Changes
+++ b/Changes
@@ -1,4 +1,4 @@
-0.55.6 2016-08-05
+0.55.6 2016-08-06
         - [bugfix] distance with key "t" uses default foundry (diewald)
 	- [cleanup] Renamed fromJson() to fromKoral() (diewald)
 	- [cleanup] Removed deprecated methods in Krill:
@@ -17,6 +17,7 @@
 	- [feature] Differ between matching scope and match highlighting,
 	  in case the match was extended to the sentence scope (diewald)
 	- [bugfix] KoralQuery bugs are now correctly moved to responses (diewald)
+	- [security] Do not mirror arbitrary JSON objects (diewald)
 
 0.55.5 2016-05-02
 	- [performance] Changed to a dynamic window for sorting in FocusSpans (margaretha)
diff --git a/src/main/java/de/ids_mannheim/korap/response/Message.java b/src/main/java/de/ids_mannheim/korap/response/Message.java
index 975f9f6..8da0ad3 100644
--- a/src/main/java/de/ids_mannheim/korap/response/Message.java
+++ b/src/main/java/de/ids_mannheim/korap/response/Message.java
@@ -116,8 +116,12 @@
      * @return Message object for chaining
      */
     public Message addParameter (String param) {
+        if (param == null || param.length() == 0)
+            return this;
+
         if (this.parameters == null)
             this.parameters = new LinkedList<String>();
+
         this.parameters.add(param);
         return this;
     };
diff --git a/src/test/java/de/ids_mannheim/korap/index/TestSegmentNegationIndex.java b/src/test/java/de/ids_mannheim/korap/index/TestSegmentNegationIndex.java
index 85161ab..81a5ed6 100644
--- a/src/test/java/de/ids_mannheim/korap/index/TestSegmentNegationIndex.java
+++ b/src/test/java/de/ids_mannheim/korap/index/TestSegmentNegationIndex.java
@@ -103,7 +103,7 @@
         assertEquals("Warning text", kr.getWarning(0).getMessage(),
                 "Exclusivity of query is ignored");
 
-	// Flag parameter injection
+        // Flag parameter injection
         kr = ki.search(new Krill(
                 "{\"query\" : { \"@type\" : \"koral:token\", \"wrap\" : { \"@type\" : \"koral:term\", \"key\" : \"a\", \"flags\" : [{ \"injection\" : true }], \"layer\" : \"orth\", \"match\" : \"match:ne\" }}}"));