diff --git a/src/array_partition.jl b/src/array_partition.jl
index a1220451..9504b7a9 100644
--- a/src/array_partition.jl
+++ b/src/array_partition.jl
@@ -572,7 +572,7 @@ end
 @inline function unpack_args(i, args::Tuple)
     return (unpack(args[1], i), unpack_args(i, Base.tail(args))...)
 end
-unpack_args(i, args::Tuple{Any}) = (unpack(args[1], i),)
+@inline unpack_args(i, args::Tuple{Any}) = (unpack(args[1], i),)
 unpack_args(::Any, args::Tuple{}) = ()
 
 ## utils
diff --git a/test/Core/partitions_test.jl b/test/Core/partitions_test.jl
index 93a3e7b8..c5b4debf 100644
--- a/test/Core/partitions_test.jl
+++ b/test/Core/partitions_test.jl
@@ -416,3 +416,14 @@ end
 struct TestIsnanFunctor end
 (::TestIsnanFunctor)(x) = isnan(x)
 @test all(TestIsnanFunctor(), AP[[NaN], [NaN]])
+
+@testset "Mixed-eltype in-place broadcast does not allocate" begin
+    # unpack_args(i, ::Tuple{Any}) was missing @inline, forcing a runtime
+    # dispatch at the tuple-recursion base case whenever the partitions
+    # have different element types.
+    f!(a, b, c, d) = (@. a = b + c * d; nothing)
+    mk() = ArrayPartition(rand(10), rand(Float32, 20), rand(5))
+    a, b, c, d = mk(), mk(), mk(), mk()
+    f!(a, b, c, d)
+    @test (@allocated f!(a, b, c, d)) == 0
+end