diff --git a/hw4.py b/hw4.py
index ce11219..f8c83ed 100644
--- a/hw4.py
+++ b/hw4.py
@@ -62,7 +62,7 @@ class QuotientRing():
         nils = []
         phi = len([ i for i in range(1, self.m) if gcd(i, self.m) == 1 ])
         for zero_div in self.zero_divisors:
-            for i in range(self.m):
+            for i in range(phi+1):
                if len((zero_div ** i % self.f).poly) == 0:
                    nils.append(zero_div)
                    break