diff --git a/klippy/mathutil.py b/klippy/mathutil.py
index ed330c61..82f12b9c 100644
--- a/klippy/mathutil.py
+++ b/klippy/mathutil.py
@@ -3,7 +3,7 @@
 # Copyright (C) 2018  Kevin O'Connor <kevin@koconnor.net>
 #
 # This file may be distributed under the terms of the GNU GPLv3 license.
-import math, logging, multiprocessing
+import math, logging, multiprocessing, traceback
 
 
 ######################################################################
@@ -51,8 +51,13 @@ def coordinate_descent(adj_params, params, error_func):
 def background_coordinate_descent(printer, adj_params, params, error_func):
     parent_conn, child_conn = multiprocessing.Pipe()
     def wrapper():
-        res = coordinate_descent(adj_params, params, error_func)
-        child_conn.send(res)
+        try:
+            res = coordinate_descent(adj_params, params, error_func)
+        except:
+            child_conn.send((True, traceback.format_exc()))
+            child_conn.close()
+            return
+        child_conn.send((False, res))
         child_conn.close()
     # Start a process to perform the calculation
     calc_proc = multiprocessing.Process(target=wrapper)
@@ -68,7 +73,9 @@ def background_coordinate_descent(printer, adj_params, params, error_func):
             gcode.respond_info("Working on calibration...", log=False)
         eventtime = reactor.pause(eventtime + .1)
     # Return results
-    res = parent_conn.recv()
+    is_err, res = parent_conn.recv()
+    if is_err:
+        raise Exception("Error in coordinate descent: %s" % (res,))
     calc_proc.join()
     parent_conn.close()
     return res