Stiffness with the Pinky Count

I'm having an issue with the Pinky Count. I'm guessing a lot of you have experienced this. I'm really struggling with it because when I hold the deck in Mechanic's Grip, my middle and ring fingers get really stiff, gripping the pack. This makes it really hard for my pinky to count/release cards because my ring finger keeps them pressed together. If anyone else has experienced this, can you tell me the secret to relaxing these two fingers (middle and ring)? I think I've explained it well, but if it's not clear, is there any way to attach a photo?