diff --git a/fib.py b/fib.py
index 421cfab..aa3dadf 100644
--- a/fib.py
+++ b/fib.py
@@ -6,6 +6,13 @@
 Negative numbers should return None
 """
 def fibonacci(position):
+
+  if (position == 0):
+    return 0
+
+  if(position<0):
+    return None
+
   if(position == 1 or position == 2):
     return 1
   return fibonacci(position - 1) + fibonacci(position - 2)