Are the straps going through the buckle the correct way. If you can alter the way they thread through so they are gripped at a greater angle it will hold more tightly.
Failing that moving where the buckle is can help, try and place it more on top of your foot.
Are the straps going through the buckle the correct way. If you can alter the way they thread through so they are gripped at a greater angle it will hold more tightly.
Failing that moving where the buckle is can help, try and place it more on top of your foot.