Alfie May scored the only goal as Cheltenham stretched their unbeaten league run to five games with a win at Charlton.
May pounced late to grab the three points following a mistake by goalkeeper Craig MacGillivray.
The only action of note in the first half fell to the visitors as they were denied three times in quick succession.
May's lob hit the crossbar and fell for Dan N'Lundulu but his effort was blocked by Lucas Ness.
With the ball loose, Ryan Inniss had to clear off the line following another follow-up from James Olayinka.
Charlton were brighter after the break and forced a number of corners to test the Cheltenham defence before the visitors started to apply some pressure of their own.
They netted the winner with six minutes left when May pounced after MacGillivray lost the ball on the edge of the area.