diff --git a/fib.py b/fib.py
index 421cfab..b2317b7 100644
--- a/fib.py
+++ b/fib.py
@@ -6,8 +6,12 @@
 Negative numbers should return None
 """
 def fibonacci(position):
-  if(position == 1 or position == 2):
+  if(position == 0):
+    return 0
+  elif (position == 1):
     return 1
+  if (position < 0):
+    return None
   return fibonacci(position - 1) + fibonacci(position - 2)