diff --git a/CHANGELOG.md b/CHANGELOG.md
index cd47bd9..204ce06 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -14,6 +14,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixed
 ### Security
 
+## 0.8.23
+
+### Fixed
+
+- eliminate `Union` in `as(SArray{}, ...)` implementation
+
 ## 0.8.22
 
 ### Fixed
diff --git a/Project.toml b/Project.toml
index 919a63d..fbaf4d3 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,7 +1,7 @@
 name = "TransformVariables"
 uuid = "84d833dd-6860-57f9-a1a7-6da5db126cff"
 authors = ["Tamas K. Papp <tkpapp@gmail.com>"]
-version = "0.8.22"
+version = "0.8.23"
 
 [deps]
 ArgCheck = "dce04be8-c92d-5529-be00-80e4d2c0e197"
diff --git a/src/aggregation.jl b/src/aggregation.jl
index f124c29..d42f57a 100644
--- a/src/aggregation.jl
+++ b/src/aggregation.jl
@@ -207,15 +207,15 @@ function transform_with(flag::LogJacFlag, transformation::StaticArrayTransformat
     y1, ℓ1, index1 = transform_with(flag, inner_transformation, x, index)
     D == 1 && return SArray{S}(y1), ℓ1, index1
     ℓ = Ref(ℓ1)
-    index = Ref(index1)
+    cum_index = Ref(index1)
     function _f(_)
-        y, ℓΔ, index′ = transform_with(flag, inner_transformation, x, index[])
-        index[] = index′
+        y, ℓΔ, index′ = transform_with(flag, inner_transformation, x, cum_index[])
+        cum_index[] = index′
         ℓ[] += ℓΔ
         y
     end
     yrest = SVector{D-1}(_f(i) for i in 2:D)
-    SArray{S}(pushfirst(yrest, y1)), ℓ[], index[]
+    SArray{S}(pushfirst(yrest, y1)), ℓ[], cum_index[]
 end
 
 function inverse_eltype(transformation::Union{ArrayTransformation,StaticArrayTransformation},