diff --git a/base/abstractarraymath.jl b/base/abstractarraymath.jl
index ee208780fffa2..2f6b5885b5fa5 100644
--- a/base/abstractarraymath.jl
+++ b/base/abstractarraymath.jl
@@ -37,6 +37,7 @@ See also [`reshape`](@ref).
 """
 vec(a::AbstractArray) = reshape(a,_length(a))
 vec(a::AbstractVector) = a
+vec(a::RowVector) = a.vec
 
 _sub(::Tuple{}, ::Tuple{}) = ()
 _sub(t::Tuple, ::Tuple{}) = t
diff --git a/base/linalg/dense.jl b/base/linalg/dense.jl
index 8b75edbef4686..6e7ae2b9e4b0a 100644
--- a/base/linalg/dense.jl
+++ b/base/linalg/dense.jl
@@ -306,7 +306,7 @@ julia> diag(A,1)
  6
 ```
 """
-diag(A::AbstractMatrix, k::Integer=0) = A[diagind(A,k)]
+diag(A::AbstractMatrix, k::Integer=0) = vec(A[diagind(A,k)])
 
 """
     diagm(kv::Pair{<:Integer,<:AbstractVector}...)