diff --git a/app.py b/app.py
index 2e73b24..6aa37cf 100644
--- a/app.py
+++ b/app.py
@@ -50,7 +50,7 @@ def doppler():
     departure_time = datetime.strptime(request.json.get('departure_time', ''),
                                        format)
     satellite = ephem.readtle(sat, sat_line_1, sat_line_2)
-    print(pass_time + " " + str(local2utc(pass_time)))
+    print(str(pass_time) + " " + str(local2utc(pass_time)))
     shift_array = []
     while pass_time < departure_time:
         AZ, EI, SHITF_UP, SHIFT_DOWN, DIS = head.CAL_DATA(