diff --git a/src/org/antlr/v4/server/JsonSerializer.java b/src/org/antlr/v4/server/JsonSerializer.java
index 15163a7..bb57812 100644
--- a/src/org/antlr/v4/server/JsonSerializer.java
+++ b/src/org/antlr/v4/server/JsonSerializer.java
@@ -107,7 +107,8 @@ public static JsonObject toJSON(Tree t, Parser recog) throws IOException {
             return null;
         }
         TokenStream tokenStream = recog.getInputStream();
-        CharStream inputStream = tokenStream.getTokenSource().getInputStream();
+//        CharStream inputStream = tokenStream.getTokenSource().getInputStream();
+        CharStream inputStream = null; // don't send input back to client (they have it and it can be big)
         return toJSON(t, Arrays.asList(ruleNames), recog.getVocabulary(), tokenStream, inputStream,
                 null, null, null);
     }