diff --git a/owlps-positioning/src/inputdatareader.cc b/owlps-positioning/src/inputdatareader.cc
index 4ca8062..cec622c 100644
--- a/owlps-positioning/src/inputdatareader.cc
+++ b/owlps-positioning/src/inputdatareader.cc
@@ -175,12 +175,12 @@ void InputDataReader::read_from_reference_points_media()
     {
       while (! (*i)->eof())
         {
-          Request &request =
-            const_cast<Request&>((*i)->get_next_request()) ;
+          const Request &request = (*i)->get_next_request() ;
           if (! request)
             continue ;
           CalibrationRequest *calibration_request =
-            dynamic_cast<CalibrationRequest*>(&request) ;
+            dynamic_cast<CalibrationRequest*>(
+              const_cast<Request*>(&request)) ;
 
           if (calibration_request == NULL)
             cerr << "Warning! Invalid calibration request at line "
diff --git a/owlps-positioning/src/request.hh b/owlps-positioning/src/request.hh
index 59fb421..282af2f 100644
--- a/owlps-positioning/src/request.hh
+++ b/owlps-positioning/src/request.hh
@@ -164,7 +164,8 @@ inline bool Request::operator!=(const Request &comp) const
 
 /**
  * @return \em false if the Request is empty.
- * @return \em true if at least one attribute is initialised.
+ * @return \em true if at least one attribute (other than #type) is
+ * initialised.
  */
 inline Request::operator bool() const
 {