diff --git a/fib.py b/fib.py
index 421cfab..342cc34 100644
--- a/fib.py
+++ b/fib.py
@@ -6,9 +6,14 @@
 Negative numbers should return None
 """
 def fibonacci(position):
-  if(position == 1 or position == 2):
-    return 1
-  return fibonacci(position - 1) + fibonacci(position - 2)
+    if position < 0:
+        return None
+    elif position == 0:
+        return 0
+    elif position == 1:
+        return 1
+    else:
+        return fibonacci(position - 1) + fibonacci(position - 2)