diff --git a/base/array.jl b/base/array.jl
index b20fe0f8d17e6..7bf843742a7ca 100644
--- a/base/array.jl
+++ b/base/array.jl
@@ -668,21 +668,23 @@ function push!(a::Array{Any,1}, item::ANY)
     return a
 end
 
-function append!{T}(a::Array{T,1}, items::Vector)
+function append!{T}(a::Array{T,1}, items::AbstractVector)
     if is(T,None)
         error(_grow_none_errmsg)
     end
     n = length(items)
+    a === items && (items = copy(items))
     ccall(:jl_array_grow_end, Void, (Any, Uint), a, n)
     a[end-n+1:end] = items
     return a
 end
 
-function prepend!{T}(a::Array{T,1}, items::Array{T,1})
+function prepend!{T}(a::Array{T,1}, items::AbstractVector)
     if is(T,None)
         error(_grow_none_errmsg)
     end
     n = length(items)
+    a === items && (items = copy(items))
     ccall(:jl_array_grow_beg, Void, (Any, Uint), a, n)
     a[1:n] = items
     return a