diff --git a/algo.py b/algo.py
index 44a45ee9f5654ca66ae2fe5a2aa1924053be8db1..76121b890fb28a540acd242eb4f7ba0cbd8d9ee8 100644
--- a/algo.py
+++ b/algo.py
@@ -110,8 +110,9 @@ def fermat_factorization(n):
     """
     
     a = math.ceil(math.sqrt(n))
+    # a = 26262277040 - 10
     b = 0
-    while(True):
+    while(a <= n): # a cannot be greater than n, because : n = (a + b) * q > 0 => a <= n
         b2 = a**2 - n
         
         if (is_square(b2)):
@@ -120,6 +121,8 @@ def fermat_factorization(n):
         
         a += 1
         
+    if(a > n): print("The Fermat's factorization didn't work on n")
+    
     return (a, b)
 
 def decode_msg(M):