diff --git a/project_euler/problem_04/sol1.py b/project_euler/problem_04/sol1.py
index 227b594d0..42f56f3ef 100644
--- a/project_euler/problem_04/sol1.py
+++ b/project_euler/problem_04/sol1.py
@@ -8,7 +8,7 @@ is less than N.
 """
 
 
-def solution(n):
+def solution(n: int = 998001) -> int:
     """Returns the largest palindrome made from the product of two 3-digit
     numbers which is less than n.
 
diff --git a/project_euler/problem_04/sol2.py b/project_euler/problem_04/sol2.py
index 0f185f121..8ee082ad2 100644
--- a/project_euler/problem_04/sol2.py
+++ b/project_euler/problem_04/sol2.py
@@ -8,7 +8,7 @@ is less than N.
 """
 
 
-def solution(n):
+def solution(n: int = 998001) -> int:
     """Returns the largest palindrome made from the product of two 3-digit
     numbers which is less than n.
 
@@ -22,8 +22,8 @@ def solution(n):
     answer = 0
     for i in range(999, 99, -1):  # 3 digit numbers range from 999 down to 100
         for j in range(999, 99, -1):
-            t = str(i * j)
-            if t == t[::-1] and i * j < n:
+            product_string = str(i * j)
+            if product_string == product_string[::-1] and i * j < n:
                 answer = max(answer, i * j)
     return answer