diff --git a/lib/pure/asyncdispatch.nim b/lib/pure/asyncdispatch.nim
index 70d94b023e546..37bc78d262c67 100644
--- a/lib/pure/asyncdispatch.nim
+++ b/lib/pure/asyncdispatch.nim
@@ -353,9 +353,19 @@ when defined(windows) or defined(nimdoc):
 
   var gDisp{.threadvar.}: owned PDispatcher ## Global dispatcher
 
+  proc close*(disp: PDispatcher) =
+    if disp.isNil: return
+    assert disp.callbacks.len == 0
+    assert disp.timers.len == 0
+    assert disp.handles.len == 0
+    if disp.ioPort != 0:
+      if closeHandle(disp.ioPort) == 0:
+        raiseOSError(osLastError())
+      disp.ioPort = 0
+
   proc setGlobalDispatcher*(disp: sink PDispatcher) =
     if not gDisp.isNil:
-      assert gDisp.callbacks.len == 0
+      close(gDisp)
     gDisp = disp
     initCallSoonProc()
 
@@ -1120,14 +1130,29 @@ when defined(windows) or defined(nimdoc):
     doAssert(ev.hWaiter != 0, "Event is not registered in the queue!")
     let p = getGlobalDispatcher()
     p.handles.excl(AsyncFD(ev.hEvent))
-    if unregisterWait(ev.hWaiter) == 0:
+    let waitFd = ev.hWaiter
+    ev.hWaiter = 0
+    if unregisterWait(waitFd) == 0:
       let err = osLastError()
       if err.int32 != ERROR_IO_PENDING:
         raiseOSError(err)
-    ev.hWaiter = 0
+    else:
+      deallocShared(cast[pointer](ev.pcd))
+      ev.pcd = nil
 
   proc close*(ev: AsyncEvent) =
     ## Closes event `ev`.
+    if ev.hWaiter != 0:
+      unregister(ev)
+      if closeHandle(ev.hEvent) == 0:
+        raiseOSError(osLastError())
+      if ev.pcd != nil:
+        # Unregistration completed asynchronously; event callback will free the
+        # registration state and then release the event object itself.
+        ev.hEvent = 0
+      else:
+        deallocShared(cast[pointer](ev))
+      return
     let res = closeHandle(ev.hEvent)
     deallocShared(cast[pointer](ev))
     if res == 0:
@@ -1146,23 +1171,40 @@ when defined(windows) or defined(nimdoc):
     proc eventcb(fd: AsyncFD, bytesCount: DWORD, errcode: OSErrorCode) =
       if ev.hWaiter != 0:
         if cb(fd):
-          # we need this check to avoid exception, if `unregister(event)` was
-          # called in callback.
-          deallocShared(cast[pointer](pcd))
           if ev.hWaiter != 0:
-            unregister(ev)
+            let waitFd = ev.hWaiter
+            ev.hWaiter = 0
+            p.handles.excl(fd)
+            if unregisterWait(waitFd) == 0:
+              let err = osLastError()
+              if err.int32 != ERROR_IO_PENDING:
+                raiseOSError(err)
+          deallocShared(cast[pointer](pcd))
+          ev.pcd = nil
+          if ev.hEvent == 0:
+            deallocShared(cast[pointer](ev))
         else:
           # if callback returned `false`, then it wants to be called again, so
           # we need to ref and protect `pcd.ovl` again, because it will be
           # unrefed and disposed in `poll()`.
-          GC_ref(pcd.ovl)
-          pcd.ovl.data.cell = system.protect(rawEnv(pcd.ovl.data.cb))
+          if ev.hWaiter != 0:
+            GC_ref(pcd.ovl)
+            pcd.ovl.data.cell = system.protect(rawEnv(pcd.ovl.data.cb))
+          else:
+            deallocShared(cast[pointer](pcd))
+            ev.pcd = nil
+            if ev.hEvent == 0:
+              deallocShared(cast[pointer](ev))
       else:
         # if ev.hWaiter == 0, then event was unregistered before `poll()` call.
         deallocShared(cast[pointer](pcd))
+        ev.pcd = nil
+        if ev.hEvent == 0:
+          deallocShared(cast[pointer](ev))
 
     registerWaitableHandle(p, hEvent, flags, pcd, INFINITE, eventcb)
     ev.hWaiter = pcd.waitFd
+    ev.pcd = pcd
 
   initAll()
 else:
@@ -1218,16 +1260,27 @@ else:
 
   when defined(nuttx):
     import std/exitprocs
+    proc close*(disp: PDispatcher)
 
     proc cleanDispatcher() {.noconv.} =
+      close(gDisp)
       gDisp = nil
 
     proc addFinalyzer() =
       addExitProc(cleanDispatcher)
 
+  proc close*(disp: PDispatcher) =
+    if disp.isNil: return
+    assert disp.callbacks.len == 0
+    assert disp.timers.len == 0
+    assert disp.selector.isNil or disp.selector.isEmpty()
+    if not disp.selector.isNil:
+      disp.selector.close()
+      disp.selector = nil
+
   proc setGlobalDispatcher*(disp: owned PDispatcher) =
     if not gDisp.isNil:
-      assert gDisp.callbacks.len == 0
+      close(gDisp)
     gDisp = disp
     initCallSoonProc()
 
diff --git a/lib/pure/ioselects/ioselectors_kqueue.nim b/lib/pure/ioselects/ioselectors_kqueue.nim
index 513578eda64c8..70d8a79bc6eb4 100644
--- a/lib/pure/ioselects/ioselectors_kqueue.nim
+++ b/lib/pure/ioselects/ioselectors_kqueue.nim
@@ -126,6 +126,7 @@ proc close*[T](s: Selector[T]) =
   let res2 = posix.close(s.sock)
   when hasThreadSupport:
     deinitLock(s.changesLock)
+    deallocSharedArray(s.changes)
     deallocSharedArray(s.fds)
     deallocShared(cast[pointer](s))
   if res1 != 0 or res2 != 0:
diff --git a/tests/async/tasyncdispatch_dispatcher_fdleak.nim b/tests/async/tasyncdispatch_dispatcher_fdleak.nim
new file mode 100644
index 0000000000000..3601235e8b97f
--- /dev/null
+++ b/tests/async/tasyncdispatch_dispatcher_fdleak.nim
@@ -0,0 +1,21 @@
+discard """
+  output: "closed"
+"""
+
+when defined(windows):
+  echo "closed"
+else:
+  import asyncdispatch, selectors, posix
+
+  block:
+    let disp = newDispatcher()
+    let fd = getFd(getIoHandler(disp))
+    disp.close()
+    doAssert fcntl(fd.cint, F_GETFD) == -1
+
+  block:
+    let fd = getFd(getIoHandler(getGlobalDispatcher()))
+    setGlobalDispatcher(nil)
+    doAssert fcntl(fd.cint, F_GETFD) == -1
+
+  echo "closed"
diff --git a/tests/async/tasyncevent_memleak.nim b/tests/async/tasyncevent_memleak.nim
new file mode 100644
index 0000000000000..f84dcf6f97a41
--- /dev/null
+++ b/tests/async/tasyncevent_memleak.nim
@@ -0,0 +1,27 @@
+discard """
+  cmd: "nim c -r --threads:on --mm:orc $file"
+  output: "0"
+"""
+
+when defined(windows):
+  import asyncdispatch
+
+  let before = getOccupiedSharedMem()
+
+  block:
+    let ev = newAsyncEvent()
+    addEvent(ev) do (fd: AsyncFD) -> bool:
+      true
+    ev.close()
+
+  block:
+    let ev = newAsyncEvent()
+    addEvent(ev) do (fd: AsyncFD) -> bool:
+      true
+    ev.unregister()
+    ev.close()
+
+  setGlobalDispatcher(nil)
+  echo getOccupiedSharedMem() - before
+else:
+  echo 0
diff --git a/tests/async/tioselectors_memleak.nim b/tests/async/tioselectors_memleak.nim
new file mode 100644
index 0000000000000..48d4a8e5e436f
--- /dev/null
+++ b/tests/async/tioselectors_memleak.nim
@@ -0,0 +1,14 @@
+discard """
+  cmd: "nim c -r --threads:on -d:threadsafe --mm:orc $file"
+  output: "0"
+"""
+
+import selectors
+
+let before = getOccupiedSharedMem()
+
+block:
+  let selector = newSelector[int]()
+  selector.close()
+
+echo getOccupiedSharedMem() - before