diff --git a/src/PreallocationTools.jl b/src/PreallocationTools.jl
index ced6354..9834c81 100644
--- a/src/PreallocationTools.jl
+++ b/src/PreallocationTools.jl
@@ -129,27 +129,39 @@ const dualcache = DiffCache
 Returns the `Dual` or normal cache array stored in `dc` based on the type of `u`.
 """
 function get_tmp(dc::DiffCache, u::T) where {T <: ForwardDiff.Dual}
-    nelem = div(sizeof(T), sizeof(eltype(dc.dual_du))) * length(dc.du)
-    if nelem > length(dc.dual_du)
-        enlargediffcache!(dc, nelem)
+    if isbitstype(T)
+        nelem = div(sizeof(T), sizeof(eltype(dc.dual_du))) * length(dc.du)
+        if nelem > length(dc.dual_du)
+            enlargediffcache!(dc, nelem)
+        end
+        _restructure(dc.du, reinterpret(T, view(dc.dual_du, 1:nelem)))
+    else
+        _restructure(dc.du, zeros(T, size(dc.du)))
     end
-    _restructure(dc.du, reinterpret(T, view(dc.dual_du, 1:nelem)))
 end
 
 function get_tmp(dc::DiffCache, ::Type{T}) where {T <: ForwardDiff.Dual}
-    nelem = div(sizeof(T), sizeof(eltype(dc.dual_du))) * length(dc.du)
-    if nelem > length(dc.dual_du)
-        enlargediffcache!(dc, nelem)
+    if isbitstype(T)
+        nelem = div(sizeof(T), sizeof(eltype(dc.dual_du))) * length(dc.du)
+        if nelem > length(dc.dual_du)
+            enlargediffcache!(dc, nelem)
+        end
+        _restructure(dc.du, reinterpret(T, view(dc.dual_du, 1:nelem)))
+    else
+        _restructure(dc.du, zeros(T, size(dc.du)))
     end
-    _restructure(dc.du, reinterpret(T, view(dc.dual_du, 1:nelem)))
 end
 
 function get_tmp(dc::DiffCache, u::AbstractArray{T}) where {T <: ForwardDiff.Dual}
-    nelem = div(sizeof(T), sizeof(eltype(dc.dual_du))) * length(dc.du)
-    if nelem > length(dc.dual_du)
-        enlargediffcache!(dc, nelem)
+    if isbitstype(T)
+        nelem = div(sizeof(T), sizeof(eltype(dc.dual_du))) * length(dc.du)
+        if nelem > length(dc.dual_du)
+            enlargediffcache!(dc, nelem)
+        end
+        _restructure(dc.du, reinterpret(T, view(dc.dual_du, 1:nelem)))
+    else
+        _restructure(dc.du, zeros(T, size(dc.du)))
     end
-    _restructure(dc.du, reinterpret(T, view(dc.dual_du, 1:nelem)))
 end
 
 function get_tmp(dc::DiffCache, u::Union{Number, AbstractArray})