Freelance to Full time Transition Hurdle

I'm a marketing professional with 6+ years of work exp (4 yrs full-time + 2.5 yrs freelance). Finding it difficult to transition back to full-time as companies only keep considering my previous CTC based on my full-time role, though I was earning much higher through freelancing. How do I negotiate to be compensated fairly based on how much I was earning as a freelancer? Any strategies/tips are welcome :)