diff --git a/koans/lib.py b/koans/lib.py
index 0b0582a..9bb5f73 100644
--- a/koans/lib.py
+++ b/koans/lib.py
@@ -4,7 +4,7 @@ from datetime import datetime
 
 
 def minify(content: str, maxlength: int, strip: Optional[str] = ' ', newlines: str = ' '):
-    content.replace('\n', newlines)
+    content = content.replace('\n', newlines)
     if strip:
         content = content.strip(strip)