Sagging power cable at IEC outlet - any remedies?

My power amp has its IEC outlet going into the back flat, and every cord I have tried including the light stock cord sag from the cords weight behind the amp. So in all likelihood the connection isn't as strong as it should be. I know connection strength matters at the other end of the cord going in to the wall outlet, is it the same here?

For others suffering from this problem have you found a way to prevent the cord sagging out?