diff --git a/src/core/ev.c b/src/core/ev.c
index 79b9c02c..19d4b39a 100644
--- a/src/core/ev.c
+++ b/src/core/ev.c
@@ -524,9 +524,9 @@ static void janet_schedule_general(JanetFiber *fiber, Janet value, JanetSignal s
     fiber->gc.flags |= JANET_FIBER_FLAG_ROOT;
     if (sig == JANET_SIGNAL_ERROR) fiber->gc.flags |= JANET_FIBER_EV_FLAG_CANCELED;
     if (soon) {
-        janet_q_push_head(&janet_vm.spawn, &t, sizeof(t));
+        janet_assert(!janet_q_push_head(&janet_vm.spawn, &t, sizeof(t)), "schedule queue overflow");
     } else {
-        janet_q_push(&janet_vm.spawn, &t, sizeof(t));
+        janet_assert(!janet_q_push(&janet_vm.spawn, &t, sizeof(t)), "schedule queue overflow");
     }
 }
 
@@ -959,11 +959,12 @@ static void janet_thread_chan_cb(JanetEVGenericMessage msg) {
             janet_schedule(fiber, janet_wrap_nil());
         }
     } else if (mode != JANET_CP_MODE_CLOSE) {
-        /* Fiber has already been cancelled or resumed. */
+        /* Fiber has already been canceled or resumed. */
         /* Resend event to another waiting thread, depending on mode */
         int is_read = (mode == JANET_CP_MODE_CHOICE_READ) || (mode == JANET_CP_MODE_READ);
         if (is_read) {
             JanetChannelPending reader;
+            int sent = 0;
             while (!janet_q_pop(&channel->read_pending, &reader, sizeof(reader))) {
                 JanetVM *vm = reader.thread;
                 if (!vm) continue;
@@ -974,8 +975,12 @@ static void janet_thread_chan_cb(JanetEVGenericMessage msg) {
                 msg.argp = channel;
                 msg.argj = x;
                 janet_ev_post_event(vm, janet_thread_chan_cb, msg);
+                sent = 1;
                 break;
             }
+            if (!sent) {
+                janet_chan_unpack(channel, &x, 1);
+            }
         } else {
             JanetChannelPending writer;
             while (!janet_q_pop(&channel->write_pending, &writer, sizeof(writer))) {
@@ -1001,14 +1006,14 @@ static void janet_thread_chan_cb(JanetEVGenericMessage msg) {
 static int janet_channel_push_with_lock(JanetChannel *channel, Janet x, int mode) {
     JanetChannelPending reader;
     int is_empty;
-    if (janet_chan_pack(channel, &x)) {
-        janet_chan_unlock(channel);
-        janet_panicf("failed to pack value for channel: %v", x);
-    }
     if (channel->closed) {
         janet_chan_unlock(channel);
         janet_panic("cannot write to closed channel");
     }
+    if (janet_chan_pack(channel, &x)) {
+        janet_chan_unlock(channel);
+        janet_panicf("failed to pack value for channel: %v", x);
+    }
     int is_threaded = janet_chan_is_threaded(channel);
     if (is_threaded) {
         /* don't dereference fiber from another thread */
@@ -1021,6 +1026,7 @@ static int janet_channel_push_with_lock(JanetChannel *channel, Janet x, int mode
     if (is_empty) {
         /* No pending reader */
         if (janet_q_push(&channel->items, &x, sizeof(Janet))) {
+            janet_chan_unpack(channel, &x, 1);
             janet_chan_unlock(channel);
             janet_panicf("channel overflow: %v", x);
         } else if (janet_q_count(&channel->items) > channel->limit) {
@@ -1054,6 +1060,9 @@ static int janet_channel_push_with_lock(JanetChannel *channel, Janet x, int mode
             msg.argj = x;
             if (vm) {
                 janet_ev_post_event(vm, janet_thread_chan_cb, msg);
+            } else {
+                /* If no vm to send to, we must clean up (unpack) the packed payload to avoid leak */
+                janet_chan_unpack(channel, &x, 1);
             }
         } else {
             if (reader.mode == JANET_CP_MODE_CHOICE_READ) {
@@ -1458,11 +1467,12 @@ static void *janet_chanat_unmarshal(JanetMarshalContext *ctx) {
     int32_t limit = janet_unmarshal_int(ctx);
     int32_t count = janet_unmarshal_int(ctx);
     if (count < 0) janet_panic("invalid negative channel count");
+    if (count > limit) janet_panic("invalid channel count");
     janet_chan_init(abst, limit, 0);
     abst->closed = !!is_closed;
     for (int32_t i = 0; i < count; i++) {
         Janet item = janet_unmarshal_janet(ctx);
-        janet_q_push(&abst->items, &item, sizeof(item));
+        janet_assert(!janet_q_push(&abst->items, &item, sizeof(item)), "bad unmarshal channel");
     }
     return abst;
 }