diff --git a/structio/core/kernels/fifo.py b/structio/core/kernels/fifo.py
index 1a665e8..cd76089 100644
--- a/structio/core/kernels/fifo.py
+++ b/structio/core/kernels/fifo.py
@@ -141,6 +141,9 @@ class FIFOKernel(BaseKernel):
     def check_cancelled(self):
         if self.current_task.pending_cancellation:
             self.cancel_task(self.current_task)
+        else:
+            # We reschedule the caller immediately!
+            self.run_queue.appendleft(self.current_task)
 
     def schedule_point(self):
         self.reschedule_running()
diff --git a/structio/sync.py b/structio/sync.py
index 21684d8..59f30f6 100644
--- a/structio/sync.py
+++ b/structio/sync.py
@@ -1,5 +1,5 @@
 # Task synchronization primitives
-from structio.core.syscalls import suspend
+from structio.core.syscalls import suspend, checkpoint
 from structio.core.run import current_task, current_loop
 from structio.core.abc import ChannelReader, ChannelWriter, Channel
 from structio.util.ki import enable_ki_protection
@@ -36,6 +36,7 @@ class Event:
         """
 
         if self.is_set():
+            await checkpoint()
             return
         self.waiters.append(current_task())
         await suspend()   # We get re-scheduled by set()
@@ -46,6 +47,7 @@ class Event:
         Sets the event, awaking all tasks
         that called wait() on it
         """
+
         if self.is_set():
             raise RuntimeError("the event has already been set")
         self._set = True
@@ -105,6 +107,7 @@ class Queue:
         enough space for the queue
         """
 
+        await checkpoint()
         if self.getters:
             self.getters.popleft().set()
             self.container.append(item)
@@ -123,6 +126,7 @@ class Queue:
         is empty
         """
 
+        await checkpoint()
         if self.putters:
             self.putters.popleft().set()
         if not self.container:
@@ -165,6 +169,7 @@ class MemorySendChannel(ChannelWriter):
 
     @enable_ki_protection
     async def close(self):
+        await checkpoint()
         if self._closed:
             raise IOError("cannot operate on a closed channel")
         self._closed = True
@@ -189,6 +194,7 @@ class MemoryReceiveChannel(ChannelReader):
 
     @enable_ki_protection
     async def close(self):
+        await checkpoint()
         if self._closed:
             raise IOError("cannot operate on a closed channel")
         self._closed = True
@@ -236,6 +242,7 @@ class Semaphore:
             self.waiters.append(Event())
             await self.waiters[-1].wait()
         self.owners.add(current)
+        await checkpoint()
 
     @enable_ki_protection
     async def release(self):
@@ -252,6 +259,7 @@ class Semaphore:
         self.owners.remove(current)
         if self.waiters:
             self.waiters.popleft().set()
+        await checkpoint()
 
     async def __aenter__(self):
         await self.acquire()