diff --git a/source/net/yacy/cora/document/MultiProtocolURI.java b/source/net/yacy/cora/document/MultiProtocolURI.java
index 57cc12cbc..cd888c281 100644
--- a/source/net/yacy/cora/document/MultiProtocolURI.java
+++ b/source/net/yacy/cora/document/MultiProtocolURI.java
@@ -487,7 +487,9 @@ public class MultiProtocolURI implements Serializable, Comparable<MultiProtocolU
                     || ch == '.' || ch == '!'
                     || ch == '~' || ch == '*'
                     || ch == '\'' || ch == '('
-                    || ch == ')' || ch == ';') {
+                    || ch == ')' || ch == ';'
+                    || ch == ',' || ch == '='
+                    || ch == '+') {
                 sbuf.append((char)ch);
             } else if (ch == '/') {                 // reserved, but may appear in post part where it should not be replaced
                 sbuf.append((char)ch);