diff --git a/src/cgutils.cpp b/src/cgutils.cpp
index e6e101b353149..62f31e237f4b6 100644
--- a/src/cgutils.cpp
+++ b/src/cgutils.cpp
@@ -2676,9 +2676,11 @@ static jl_cgval_t typed_store(jl_codectx_t &ctx,
                     assert(!isboxed && maybe_null_if_boxed);
                     Value *first_ptr = extract_first_ptr(ctx, realinstr);
                     assert(first_ptr != nullptr);
-                    Done = ctx.builder.CreateIsNotNull(first_ptr);
+                    // Done = Success || first_ptr != NULL
+                    Done = ctx.builder.CreateOr(Success, ctx.builder.CreateIsNotNull(first_ptr));
                 }
                 else {
+                    // Done = Success || first_ptr == NULL || oldval == cmpop)
                     // Done = !(!Success && (first_ptr != NULL && oldval == cmpop))
                     Done = emit_guarded_test(ctx, ctx.builder.CreateNot(Success), false, [&] {
                         Value *first_ptr = nullptr;
diff --git a/test/atomics.jl b/test/atomics.jl
index 3572824741459..369a63f7d5fbf 100644
--- a/test/atomics.jl
+++ b/test/atomics.jl
@@ -57,9 +57,8 @@ swap(x, y) = y
 struct UndefComplex{T}
     re::T
     im::T
-    UndefComplex{T}() where {T} = new{T}()
 end
-Base.convert(T::Type{<:UndefComplex}, S) = T()
+Base.convert(T::Type{<:UndefComplex}, S) = T(S, 0)
 
 let T1 = Refxy{NTuple{3,UInt8}},
     T2 = ARefxy{NTuple{3,UInt8}}