diff --git a/SALCAnitrate/SALCAnitrate_field.py b/SALCAnitrate/SALCAnitrate_field.py
index 94b6bec..a849f86 100644
--- a/SALCAnitrate/SALCAnitrate_field.py
+++ b/SALCAnitrate/SALCAnitrate_field.py
@@ -71,8 +71,10 @@ def c_month(in_month):
     '''
     # import the numpy module again for the SALCAfuture environment
     import numpy as np
-    # generate an array with zeros the length of the input
-    m_month = list(np.zeros(len(in_month)))
+    # copy the input so the month remapping below operates on the real event
+    # months (previously this was np.zeros, so the loop tested zeros and the
+    # function always returned an all-zeros array regardless of its input)
+    m_month = list(in_month)
     # for each month in the input list
     for i in range(len(in_month)):
         # returns 0 for no event