diff --git a/project_euler/problem_025/sol2.py b/project_euler/problem_025/sol2.py
index ed3b54bb351f..b041afd98c86 100644
--- a/project_euler/problem_025/sol2.py
+++ b/project_euler/problem_025/sol2.py
@@ -23,9 +23,10 @@
 What is the index of the first term in the Fibonacci sequence to contain 1000
 digits?
 """
+from typing import Generator
 
 
-def fibonacci_generator() -> int:
+def fibonacci_generator() -> Generator[int, None, None]:
     """
     A generator that produces numbers in the Fibonacci sequence