diff --git a/src/core/ev.c b/src/core/ev.c
index a3eb06ef..25fb221e 100644
--- a/src/core/ev.c
+++ b/src/core/ev.c
@@ -598,14 +598,15 @@ static int janet_chan_pack(JanetChannel *chan, Janet *x) {
     }
 }
 
-static int janet_chan_unpack(JanetChannel *chan, Janet *x) {
+static int janet_chan_unpack(JanetChannel *chan, Janet *x, int is_cleanup) {
     if (!janet_chan_is_threaded(chan)) return 0;
     switch (janet_type(*x)) {
         default:
             return 1;
         case JANET_BUFFER: {
             JanetBuffer *buf = janet_unwrap_buffer(*x);
-            *x = janet_unmarshal(buf->data, buf->count, JANET_MARSHAL_UNSAFE, NULL, NULL);
+            int flags = is_cleanup ? JANET_MARSHAL_UNSAFE : (JANET_MARSHAL_UNSAFE | JANET_MARSHAL_DECREF);
+            *x = janet_unmarshal(buf->data, buf->count, flags, NULL, NULL);
             janet_buffer_deinit(buf);
             janet_free(buf);
             return 0;
@@ -639,7 +640,7 @@ static void janet_chan_deinit(JanetChannel *chan) {
     if (janet_chan_is_threaded(chan)) {
         Janet item;
         while (!janet_q_pop(&chan->items, &item, sizeof(item))) {
-            janet_chan_unpack(chan, &item);
+            janet_chan_unpack(chan, &item, 1);
         }
     }
     janet_q_deinit(&chan->items);
@@ -747,12 +748,12 @@ static void janet_thread_chan_cb(JanetEVGenericMessage msg) {
     janet_ev_dec_refcount();
     if (fiber->sched_id == sched_id) {
         if (mode == JANET_CP_MODE_CHOICE_READ) {
-            janet_assert(!janet_chan_unpack(channel, &x), "packing error");
+            janet_assert(!janet_chan_unpack(channel, &x, 0), "packing error");
             janet_schedule(fiber, make_read_result(channel, x));
         } else if (mode == JANET_CP_MODE_CHOICE_WRITE) {
             janet_schedule(fiber, make_write_result(channel));
         } else if (mode == JANET_CP_MODE_READ) {
-            janet_assert(!janet_chan_unpack(channel, &x), "packing error");
+            janet_assert(!janet_chan_unpack(channel, &x, 0), "packing error");
             janet_schedule(fiber, x);
         } else if (mode == JANET_CP_MODE_WRITE) {
             janet_schedule(fiber, janet_wrap_channel(channel));
@@ -893,7 +894,7 @@ static int janet_channel_pop(JanetChannel *channel, Janet *item, int is_choice)
         }
         return 0;
     }
-    janet_assert(!janet_chan_unpack(channel, item), "bad channel packing");
+    janet_assert(!janet_chan_unpack(channel, item, 0), "bad channel packing");
     if (!janet_q_pop(&channel->write_pending, &writer, sizeof(writer))) {
         /* Pending writer */
         if (is_threaded) {
diff --git a/src/core/marsh.c b/src/core/marsh.c
index a937a70b..a9912190 100644
--- a/src/core/marsh.c
+++ b/src/core/marsh.c
@@ -1396,16 +1396,21 @@ static const uint8_t *unmarshal_one(
             } u;
             memcpy(u.bytes, data, sizeof(void *));
             data += sizeof(void *);
-            *out = janet_wrap_abstract(u.ptr);
 
-            /* Check if we have already seen this abstract type - if we have, decrement refcount */
-            Janet check = janet_table_get(&janet_vm.threaded_abstracts, *out);
-            if (janet_checktype(check, JANET_NIL)) {
-                /* Transfers reference from threaded channel buffer to current heap */
-                janet_table_put(&janet_vm.threaded_abstracts, *out, janet_wrap_false());
-            } else {
-                /* Heap reference already accounted for, remove threaded channel reference. */
+            if (flags & JANET_MARSHAL_DECREF) {
+                /* Decrement immediately and don't bother putting into heap */
                 janet_abstract_decref(u.ptr);
+                *out = janet_wrap_nil();
+            } else {
+                *out = janet_wrap_abstract(u.ptr);
+                Janet check = janet_table_get(&janet_vm.threaded_abstracts, *out);
+                if (janet_checktype(check, JANET_NIL)) {
+                    /* Transfers reference from threaded channel buffer to current heap */
+                    janet_table_put(&janet_vm.threaded_abstracts, *out, janet_wrap_false());
+                } else {
+                    /* Heap reference already accounted for, remove threaded channel reference. */
+                    janet_abstract_decref(u.ptr);
+                }
             }
 
             janet_v_push(st->lookup, *out);
@@ -1419,7 +1424,6 @@ static const uint8_t *unmarshal_one(
             return NULL;
         }
     }
-#undef EXTRA
 }
 
 Janet janet_unmarshal(
diff --git a/src/core/util.h b/src/core/util.h
index 2c7e2a0e..fb54715f 100644
--- a/src/core/util.h
+++ b/src/core/util.h
@@ -49,6 +49,8 @@
 } while (0)
 #endif
 
+#define JANET_MARSHAL_DECREF 0x40000
+
 #define janet_assert(c, m) do { \
     if (!(c)) JANET_EXIT((m)); \
 } while (0)