How to secure PC Sync cables!

Hi!! I love using flashes for my film photos, but the two I like using have PC Sync ports and no hot shoe, and I have so much trouble w keeping the cable in the port without it just falling out! I photograph shows a lot and move quickly, and Im tired of my flash not going off because I forgot to check or it got knocked/fell out of the port. Is there any way to fix this? Its loose on both the camera and flash side, and multiple cameras and flashes I’ve tried to use have had this issue. Is there something I’m missing?