diff --git a/src/abstractmps.jl b/src/abstractmps.jl
index 4670be5..bd96f45 100644
--- a/src/abstractmps.jl
+++ b/src/abstractmps.jl
@@ -1873,7 +1873,7 @@ function setindex!(
           #AC = noprime(AC * _fermionic_swap(c))
           #A = AC * dag(C)
 
-          FSWAP = _fermionic_swap(s0[1], s0[2])
+          FSWAP = adapt(datatype(A), _fermionic_swap(s0[1], s0[2]))
           A = noprime(A * FSWAP)
         end
       elseif ψ isa MPO