diff --git a/git_time_machine.py b/git_time_machine.py
index 2f32e1c..2ae8d61 100644
--- a/git_time_machine.py
+++ b/git_time_machine.py
@@ -76,12 +76,13 @@ def main(stdscr, filename):
 
         elif focus == "right":
             if key == curses.KEY_DOWN or key == ord('j'):
-                scroll_offset += 1
+                if scroll_offset < max(0, len(file_lines) - height):
+                    scroll_offset += 1
             elif key == curses.KEY_UP or key == ord('k'):
                 if scroll_offset > 0:
                     scroll_offset -= 1
             elif key == curses.KEY_NPAGE:  # Page Down
-                scroll_offset += height
+                scroll_offset = min(scroll_offset + height, max(0, len(file_lines) - height))
             elif key == curses.KEY_PPAGE:  # Page Up
                 scroll_offset = max(0, scroll_offset - height)