diff --git a/src/rulesets/Base/indexing.jl b/src/rulesets/Base/indexing.jl
index f81ffda59..ea081c99c 100644
--- a/src/rulesets/Base/indexing.jl
+++ b/src/rulesets/Base/indexing.jl
@@ -126,8 +126,11 @@ This returns roughly `dx = zero(x)`, except that this is guaranteed to be mutabl
 and its element type is wide enough to allow `setindex!(dx, dy, inds...)`, which is exactly what
 `∇getindex` does next.
 """
-_setindex_zero(x::AbstractArray{<:Number}, dy, inds::Integer...) = fill!(similar(x, typeof(dy)), false)
-_setindex_zero(x::AbstractArray{<:Number}, dy, inds...) = fill!(similar(x, eltype(dy)), false)
+_setindex_zero(x::AbstractArray{<:Number}, dy, inds::Integer...) =
+    fill!(similar(x, typeof(dy)), false)
+function _setindex_zero(x::AbstractArray{<:Number}, dy, inds...)
+    return fill!(similar(x, eltype(dy)), false)
+end
 function _setindex_zero(x::AbstractArray, dy, inds::Integer...)
     # This allows for types which don't define zero (like Vector) and types whose zero special (like Tangent),
     # but always makes an abstract type. TODO: make it infer concrete type for e.g. vectors of SVectors