diff --git a/src/dict.jl b/src/dict.jl
index 5899cf6..b28d93e 100644
--- a/src/dict.jl
+++ b/src/dict.jl
@@ -348,22 +348,24 @@ end
 
 @inline value_ref(ref::RefSlotRef) = ImmutableRef(ref.ref[].value.x)
 
-allocate_slot(::AbstractVector{Slot}) where {Slot<:Ref} = forceheap(Slot())
+allocate_slot(::AbstractVector{Slot}) where {Slot<:Ref} = Ref(Slot())
+# One indirection to force heap allocation
 
 @inline function cas_slot!(
     slotref::RefSlotRef{Slot},
-    new_slot::Slot,
+    new_slot_ref::Ref{Slot},
     root,
     key,
     value,
 ) where {P,Slot<:Ref{P}}
     ptr = slotref.ptr
+    new_slot = new_slot_ref[]
     new_slot[] = value isa NoValue ? P(key) : P(key, value)
-    ou = UInt(pointer_from_objref(slotref.ref))
-    nu = UInt(pointer_from_objref(new_slot))
-    julia_write_barrier(new_slot)
-    julia_write_barrier(root, new_slot)
-    GC.@preserve new_slot begin
+    GC.@preserve new_slot_ref begin
+        ou = UInt(pointer_from_objref(slotref.ref))
+        nu = UInt(unsafe_load(Ptr{Ptr{Cvoid}}(pointer_from_objref(new_slot_ref))))
+        julia_write_barrier(new_slot)
+        julia_write_barrier(root, new_slot)
         fu = UnsafeAtomics.cas!(Ptr{typeof(nu)}(ptr), ou, nu)
     end
     return fu == ou
diff --git a/src/utils.jl b/src/utils.jl
index 0f0afea..fd5b397 100644
--- a/src/utils.jl
+++ b/src/utils.jl
@@ -166,16 +166,6 @@ end
     end
 end
 
-const _FALSE_ = Ref(false)
-
-# TODO: a teribble hack to force heap-allocation of `x`; can we get rid of it?
-@inline function forceheap(x)
-    if _FALSE_[]
-        global SINK = x
-    end
-    return x
-end
-
 @generated function julia_write_barrier(args::Vararg{Any,N}) where {N}
     pointer_exprs = map(1:N) do i
         :(_pointer_from_objref(args[$i]))
@@ -183,7 +173,7 @@ end
     jlp = "{} addrspace(10)*"
     llvm_args = string.("%", 0:N-1)
     word = "i$(Base.Sys.WORD_SIZE)"
-    entry_sig = join(word .* llvm_args, ", ")
+    entry_sig = join(word .* " " .* llvm_args, ", ")
     ptrs = string.("%ptr", 0:N-1)
     wb_sig = join("$jlp " .* ptrs, ", ")
     inttoptr = join(