diff --git a/TODO b/TODO
index 9e55f23..69a02c2 100644
--- a/TODO
+++ b/TODO
@@ -110,9 +110,6 @@
 - Algorithms
    ° Add to the result the information "area error" (whether on not the
    computed result is in the same room as the real position).
-   ° Delete reference points after a given amount of time. This is to
-   avoid meaningless old reference points, for instance if an AP was
-   shut down.
    ° Handle the power and antenna gain difference between the
    calibration mobile (or pseudo-mobile, for autocalibration) and the
    mobile to position.
diff --git a/owlps-positioner/cfg/owlps-positioner.conf b/owlps-positioner/cfg/owlps-positioner.conf
index 4270e3a..bd0b97e 100644
--- a/owlps-positioner/cfg/owlps-positioner.conf
+++ b/owlps-positioner/cfg/owlps-positioner.conf
@@ -110,6 +110,11 @@ csv-file = /tmp/owlps-positioner.log
 # it is not activated by default for security purposes.
 #accept-new-calibration-requests = false
 
+# Maximum age of the calibration requests, in seconds. If greater than
+# zero, the positioning requests older than this timeout will be
+# deleted.
+#calibration-requests-timeout = 0
+
 # If you activate the above option and want the calibration requests
 # to be treated as positioning requests (in addition to the normal
 # treatment of calibration requests), activate this option.
diff --git a/owlps-positioner/src/positioning.cc b/owlps-positioner/src/positioning.cc
index be9e137..2f6d6e9 100644
--- a/owlps-positioner/src/positioning.cc
+++ b/owlps-positioner/src/positioning.cc
@@ -136,6 +136,12 @@ void Positioning::loop()
       if (! request)
         continue ;
 
+      unsigned int cr_timeout =
+        Configuration::uint_value(
+          "positioning.calibration-requests-timeout") ;
+      if (cr_timeout > 0)
+        Stock::delete_calibration_requests_older_than(cr_timeout) ;
+
       Point3D real_position ;
       bool compute_error = false ;
       ResultList results(&request) ;
diff --git a/owlps-positioner/src/stock.cc b/owlps-positioner/src/stock.cc
index dc46fe7..77461bb 100644
--- a/owlps-positioner/src/stock.cc
+++ b/owlps-positioner/src/stock.cc
@@ -656,6 +656,32 @@ delete_calibration_request(const CalibrationRequest &request)
 }
 
 
+/**
+ * @param timeout The maximum age of the calibration requests (seconds).
+ */
+void Stock::delete_calibration_requests_older_than(int timeout)
+{
+  assert(timeout > 0) ;
+
+  unordered_set<CalibrationRequest>::iterator cr =
+    calibration_requests.begin() ;
+  while (cr != calibration_requests.end())
+    {
+      const Timestamp &elapsed = cr->get_time_sent().elapsed() ;
+      uint64_t elapsed_sec = static_cast<uint64_t>(elapsed) / 1000 ;
+      if (elapsed_sec >= static_cast<unsigned int>(timeout))
+        {
+          ReferencePoint *rp = cr->get_reference_point() ;
+          cr = calibration_requests.erase(cr) ;
+          if (rp && rp->get_requests().empty())
+            reference_points.erase(*rp) ;
+        }
+      else
+        ++cr ;
+    }
+}
+
+
 const CalibrationRequest& Stock::
 find_create_calibration_request(const CalibrationRequest &request)
 {
diff --git a/owlps-positioner/src/stock.hh b/owlps-positioner/src/stock.hh
index 7e57cfa..568b0ce 100644
--- a/owlps-positioner/src/stock.hh
+++ b/owlps-positioner/src/stock.hh
@@ -169,6 +169,9 @@ public:
   /// Deletes a CalibrationRequest
   static void delete_calibration_request(
     const CalibrationRequest &request) ;
+  /// \brief Deletes the calibration requests that are older than
+  /// \em timeout seconds
+  static void delete_calibration_requests_older_than(int timeout) ;
   /// Searches for a CalibrationRequest and adds it if it does not exist
   static const CalibrationRequest&
   find_create_calibration_request(const CalibrationRequest &request) ;
diff --git a/owlps-positioner/src/userinterface.cc b/owlps-positioner/src/userinterface.cc
index 0bfcc44..223a87f 100644
--- a/owlps-positioner/src/userinterface.cc
+++ b/owlps-positioner/src/userinterface.cc
@@ -252,6 +252,10 @@ void UserInterface::fill_positioning_options()
    " self-calibration. If unactivated, the calibration requests"
    " are handled as positioning requests (default is unactivated,"
    " for security purposes).")
+  ("positioning.calibration-requests-timeout",
+   po::value<unsigned int>()->default_value(0),
+   "Maximum age of a calibration request before to delete it"
+   " (0 = unlimited).")
   ("positioning.position-calibration-requests",
    po::value<bool>()->default_value(false),
    "When accept-new-calibration-requests is activated, allow the"