diff --git a/include/AclRule.h b/include/AclRule.h
index 507e30b3da..ed6d402bf3 100644
--- a/include/AclRule.h
+++ b/include/AclRule.h
@@ -37,7 +37,9 @@ public:
 
     AclRule(long long _user, long long _resource, long long _rights):
         user(_user), resource(_resource), rights(_rights)
-    {};
+    {
+        build_str();
+    };
 
     bool operator ==(const AclRule& other) const
     {
@@ -51,8 +53,10 @@ public:
      *
      *    @return a human readable string for this rule
      */
-    string to_str() const;
-
+    const string& to_str() const
+    {
+        return str;
+    };
 
     /**
      *  Function to print the object into a string in XML format
@@ -124,6 +128,13 @@ private:
      *  64 bit integer containing the rights flags
      */
     long long rights;
+
+    /**
+     *  Human readable representation
+     */
+    string str;
+
+    void build_str();
 };
 
 #endif /*ACL_RULE_H*/
diff --git a/src/acl/AclRule.cc b/src/acl/AclRule.cc
index fb20d3aa9f..de9e3686ca 100644
--- a/src/acl/AclRule.cc
+++ b/src/acl/AclRule.cc
@@ -27,11 +27,10 @@ const long long AclRule::ALL_ID         = 0x400000000LL;
 /* -------------------------------------------------------------------------- */
 /* -------------------------------------------------------------------------- */
 
-string AclRule::to_str() const
+void AclRule::build_str()
 {
     ostringstream oss;
 
-    oss << "USER:";
     if ( (user & GROUP_ID) != 0 )
     {
         oss << "@" << user_id();
@@ -45,7 +44,7 @@ string AclRule::to_str() const
         oss << "*";
     }
 
-    oss << " RESOURCE:";
+    oss << " ";
 
     AuthRequest::Object objects[] = {
             AuthRequest::VM,
@@ -89,7 +88,7 @@ string AclRule::to_str() const
         oss << "*";
     }
 
-    oss << " OPERATION:";
+    oss << " ";
 
 
     AuthRequest::Operation operations[] = {
@@ -120,7 +119,7 @@ string AclRule::to_str() const
         }
     }
 
-    return oss.str();
+    str = oss.str();
 }
 
 /* -------------------------------------------------------------------------- */
@@ -135,9 +134,7 @@ string& AclRule::to_xml(string& xml) const
         "<USER>"     << hex << user      << "</USER>"        <<
         "<RESOURCE>" << hex << resource  << "</RESOURCE>"    <<
         "<RIGHTS>"   << hex << rights    << "</RIGHTS>"      <<
-
-        // TODO: Element DEBUG contains a human friendly string
-        "<DEBUG>"    << to_str()         << "</DEBUG>"       <<
+        "<STRING>"   << str              << "</STRING>"      <<
     "</RULE>";
 
     xml = oss.str();