diff --git a/src/state-tomo.jl b/src/state-tomo.jl
index 85a6d74..08cf20d 100644
--- a/src/state-tomo.jl
+++ b/src/state-tomo.jl
@@ -167,7 +167,7 @@ struct MLStateTomo
             end
         end
         sv = sum(v)
-        if ! LinearAlgebra.isdiag(sv) || !isapprox(maximum(abs.(LinearAlgebra.diag(sv)))-minimum(abs.(LinearAlgebra.diag(sv))),0.0)
+        if ! LinearAlgebra.isdiag(sv) || !isapprox(maximum(abs.(LinearAlgebra.diag(sv)))-minimum(abs.(LinearAlgebra.diag(sv))),0.0,atol=1e-12)
             error("POVM effects must add up to the identity.")
         end
         if !all([size(e,1)==size(e,2) for e in v]) || !all([size(v[1],1)==size(e,1) for e in v])