diff --git a/Makefile b/Makefile
index 2d851c9..d54cd5b 100644
--- a/Makefile
+++ b/Makefile
@@ -3,5 +3,5 @@ reference:
 	amortize -P 100000 -r 0.05 -f monthly -n 36 -s > ref.txt
 
 test:
-	python amort.py -p 100000 -i 5.0 -t 3 -ot "{\"payment_number\":13,\"amount\":5000}"
+	python src/amort.py -p 100000 -i 5.0 -t 3 -ot "{\"payment_number\":13,\"amount\":5000}"
 
diff --git a/amort.py b/src/amort.py
similarity index 84%
rename from amort.py
rename to src/amort.py
index df39cef..b06a824 100644
--- a/amort.py
+++ b/src/amort.py
@@ -1,6 +1,4 @@
 
-import argparse, json
-
 def generate_amortization_schedule(principal, interest_rate, loan_term, extra_payments=[]):
     # Convert interest rate to decimal and calculate periodic interest rate
     monthly_interest_rate = interest_rate / 12 / 100
@@ -73,7 +71,30 @@ def get_totals(amortization_schedule, func=None):
         func(messages)
     return total_paid, total_interest_paid, total_principal_paid
 
+def compare(with_extra_payments, without):
+    x,y,z = get_totals(with_extra_payments)
+    a,b,c = get_totals(without)
+    term_length = len(without) - len(with_extra_payments)
+    print(chr(916), "paid: ", round(x-a,2))
+    print(chr(916), "interest paid: ", round(y-b,2))
+    print(chr(916), "principal paid: ", round(abs(z-c),2))
+    print(chr(916), "term (months): ", term_length)
+
+def display(table):
+    print("id, paid, interest payment, principal payment, remaining")
+    for row in table:
+        print(row)
+
+def export(table, filename="schedule.csv"):
+    with open(filename, 'w') as f:
+        print("id, paid, interest payment, principal payment, remaining", file=f)
+        for row in table:
+            print(row, file=f)
+    print("wrote to file", filename)
+
 if __name__ == "__main__":
+    import argparse, json
+
     def get_arguments():
         p = argparse.ArgumentParser()
         p. add_argument("--principal", "-p", type=float, \
@@ -94,29 +115,12 @@ if __name__ == "__main__":
                 # print(extra["extra-payments"])
         if args.one_time is not None:
             l.append(json.loads(args.one_time))
-        extra = l["extra-payments"]
-        extra.sort(key=lambda k: k["payment_number"])
+        extra = []
+        if "extra-payments" in l:
+            extra = l["extra-payments"]
+            extra.sort(key=lambda k: k["payment_number"])
         return args.principal, args.interest_rate, args.term, extra
 
-    def compare(with_extra_payments, without):
-        x,y,z = get_totals(with_extra_payments)
-        a,b,c = get_totals(without)
-        print(chr(916), "paid: ", round(x-a,2))
-        print(chr(916), "interest paid: ", round(y-b,2))
-        print(chr(916), "principal paid: ", round(abs(z-c),2))
-
-    def display(table):
-        print("id, paid, interest payment, principal payment, remaining")
-        for row in table:
-            print(row)
-
-    def export(table, filename="schedule.csv"):
-        with open(filename, 'w') as f:
-            print("id, paid, interest payment, principal payment, remaining", file=f)
-            for row in table:
-                print(row, file=f)
-        print("wrote to file", filename)
-
     principal, interest_rate, loan_term, extra_payments = get_arguments()
 
     schedule = generate_amortization_schedule(principal, interest_rate, loan_term, extra_payments)