diff --git a/maths/primelib.py b/maths/primelib.py
index 9606592b1..88e1f7438 100644
--- a/maths/primelib.py
+++ b/maths/primelib.py
@@ -599,6 +599,8 @@ def fib(n):
 
     return ans
 
+
 if __name__ == "__main__":
     import doctest
+
     doctest.testmod()