diff --git a/src/levenberg.jl b/src/levenberg.jl
index f181fcfcc..39cd7ca7e 100644
--- a/src/levenberg.jl
+++ b/src/levenberg.jl
@@ -356,7 +356,7 @@ function perform_step!(cache::LevenbergMarquardtCache{false, fastls}) where {fas
 
     # Usual Levenberg-Marquardt step ("velocity").
     if fastls
-        cache.mat_tmp = vcat(J, λ .* cache.DᵀD)
+        cache.mat_tmp = _vcat(J, λ .* cache.DᵀD)
         cache.rhs_tmp[1:length(fu1)] .= -_vec(fu1)
         linres = dolinsolve(alg.precs, linsolve; A = cache.mat_tmp,
             b = cache.rhs_tmp, linu = _vec(cache.v), p = p, reltol = cache.abstol)
diff --git a/test/misc.jl b/test/misc.jl
index e00a8fb01..f976b49ae 100644
--- a/test/misc.jl
+++ b/test/misc.jl
@@ -4,4 +4,4 @@ using BandedMatrices, LinearAlgebra, NonlinearSolve, SparseArrays, Test
 b = BandedMatrix(Ones(5, 5), (1, 1))
 d = Diagonal(ones(5, 5))
 
-@test NonlinearSolve._vcat(b, d) == vcat(sparse(b), d)
+@test NonlinearSolve._vcat(b, d) == zero.(vcat(sparse(b), d))