diff --git a/dlls/api-ms-win-core-threadpool-l1-1-0/api-ms-win-core-threadpool-l1-1-0.spec b/dlls/api-ms-win-core-threadpool-l1-1-0/api-ms-win-core-threadpool-l1-1-0.spec
index a8a264182a1..52057fedcae 100644
--- a/dlls/api-ms-win-core-threadpool-l1-1-0/api-ms-win-core-threadpool-l1-1-0.spec
+++ b/dlls/api-ms-win-core-threadpool-l1-1-0/api-ms-win-core-threadpool-l1-1-0.spec
@@ -1,10 +1,10 @@
 @ stdcall CallbackMayRunLong(ptr) kernel32.CallbackMayRunLong
-@ stub CancelThreadpoolIo
+@ stdcall CancelThreadpoolIo(ptr) kernel32.CancelThreadpoolIo
 @ stdcall ChangeTimerQueueTimer(ptr ptr long long) kernel32.ChangeTimerQueueTimer
 @ stdcall CloseThreadpool(ptr) kernel32.CloseThreadpool
 @ stdcall CloseThreadpoolCleanupGroup(ptr) kernel32.CloseThreadpoolCleanupGroup
 @ stdcall CloseThreadpoolCleanupGroupMembers(ptr long ptr) kernel32.CloseThreadpoolCleanupGroupMembers
-@ stub CloseThreadpoolIo
+@ stdcall CloseThreadpoolIo(ptr) kernel32.CloseThreadpoolIo
 @ stdcall CloseThreadpoolTimer(ptr) kernel32.CloseThreadpoolTimer
 @ stdcall CloseThreadpoolWait(ptr) kernel32.CloseThreadpoolWait
 @ stdcall CloseThreadpoolWork(ptr) kernel32.CloseThreadpoolWork
@@ -36,7 +36,7 @@
 @ stdcall SubmitThreadpoolWork(ptr) kernel32.SubmitThreadpoolWork
 @ stdcall TrySubmitThreadpoolCallback(ptr ptr ptr) kernel32.TrySubmitThreadpoolCallback
 @ stdcall UnregisterWaitEx(long long) kernel32.UnregisterWaitEx
-@ stub WaitForThreadpoolIoCallbacks
+@ stdcall WaitForThreadpoolIoCallbacks(ptr) kernel32.WaitForThreadpoolIoCallbacks
 @ stdcall WaitForThreadpoolTimerCallbacks(ptr long) kernel32.WaitForThreadpoolTimerCallbacks
 @ stdcall WaitForThreadpoolWaitCallbacks(ptr long) kernel32.WaitForThreadpoolWaitCallbacks
 @ stdcall WaitForThreadpoolWorkCallbacks(ptr long) kernel32.WaitForThreadpoolWorkCallbacks
diff --git a/dlls/api-ms-win-core-threadpool-l1-2-0/api-ms-win-core-threadpool-l1-2-0.spec b/dlls/api-ms-win-core-threadpool-l1-2-0/api-ms-win-core-threadpool-l1-2-0.spec
index fc373c3c893..0c5d176c4ec 100644
--- a/dlls/api-ms-win-core-threadpool-l1-2-0/api-ms-win-core-threadpool-l1-2-0.spec
+++ b/dlls/api-ms-win-core-threadpool-l1-2-0/api-ms-win-core-threadpool-l1-2-0.spec
@@ -1,9 +1,9 @@
 @ stdcall CallbackMayRunLong(ptr) kernel32.CallbackMayRunLong
-@ stub CancelThreadpoolIo
+@ stdcall CancelThreadpoolIo(ptr) kernel32.CancelThreadpoolIo
 @ stdcall CloseThreadpool(ptr) kernel32.CloseThreadpool
 @ stdcall CloseThreadpoolCleanupGroup(ptr) kernel32.CloseThreadpoolCleanupGroup
 @ stdcall CloseThreadpoolCleanupGroupMembers(ptr long ptr) kernel32.CloseThreadpoolCleanupGroupMembers
-@ stub CloseThreadpoolIo
+@ stdcall CloseThreadpoolIo(ptr) kernel32.CloseThreadpoolIo
 @ stdcall CloseThreadpoolTimer(ptr) kernel32.CloseThreadpoolTimer
 @ stdcall CloseThreadpoolWait(ptr) kernel32.CloseThreadpoolWait
 @ stdcall CloseThreadpoolWork(ptr) kernel32.CloseThreadpoolWork
@@ -31,7 +31,7 @@
 @ stdcall StartThreadpoolIo(ptr) kernel32.StartThreadpoolIo
 @ stdcall SubmitThreadpoolWork(ptr) kernel32.SubmitThreadpoolWork
 @ stdcall TrySubmitThreadpoolCallback(ptr ptr ptr) kernel32.TrySubmitThreadpoolCallback
-@ stub WaitForThreadpoolIoCallbacks
+@ stdcall WaitForThreadpoolIoCallbacks(ptr) kernel32.WaitForThreadpoolIoCallbacks
 @ stdcall WaitForThreadpoolTimerCallbacks(ptr long) kernel32.WaitForThreadpoolTimerCallbacks
 @ stdcall WaitForThreadpoolWaitCallbacks(ptr long) kernel32.WaitForThreadpoolWaitCallbacks
 @ stdcall WaitForThreadpoolWorkCallbacks(ptr long) kernel32.WaitForThreadpoolWorkCallbacks
diff --git a/dlls/kernel32/kernel32.spec b/dlls/kernel32/kernel32.spec
index 2e2f7c9a844..a5550dd3591 100644
--- a/dlls/kernel32/kernel32.spec
+++ b/dlls/kernel32/kernel32.spec
@@ -210,7 +210,7 @@
 @ stdcall -import CancelIo(long)
 @ stdcall -import CancelIoEx(long ptr)
 @ stdcall -import CancelSynchronousIo(long)
-# @ stub CancelThreadpoolIo
+@ stdcall CancelThreadpoolIo(ptr) ntdll.TpCancelAsyncIoOperation
 @ stdcall CancelTimerQueueTimer(ptr ptr)
 @ stdcall -import CancelWaitableTimer(long)
 @ stdcall -import ChangeTimerQueueTimer(ptr ptr long long)
@@ -230,7 +230,7 @@
 @ stdcall CloseThreadpool(ptr) ntdll.TpReleasePool
 @ stdcall CloseThreadpoolCleanupGroup(ptr) ntdll.TpReleaseCleanupGroup
 @ stdcall CloseThreadpoolCleanupGroupMembers(ptr long ptr) ntdll.TpReleaseCleanupGroupMembers
-# @ stub CloseThreadpoolIo
+@ stdcall CloseThreadpoolIo(ptr) ntdll.TpReleaseIoCompletion
 @ stdcall CloseThreadpoolTimer(ptr) ntdll.TpReleaseTimer
 @ stdcall CloseThreadpoolWait(ptr) ntdll.TpReleaseWait
 @ stdcall CloseThreadpoolWork(ptr) ntdll.TpReleaseWork
@@ -1581,7 +1581,7 @@
 @ stdcall -import WaitForMultipleObjectsEx(long ptr long long long)
 @ stdcall -import WaitForSingleObject(long long)
 @ stdcall -import WaitForSingleObjectEx(long long long)
-# @ stub WaitForThreadpoolIoCallbacks
+@ stdcall WaitForThreadpoolIoCallbacks(ptr) ntdll.TpWaitForIoCompletion
 @ stdcall WaitForThreadpoolTimerCallbacks(ptr long) ntdll.TpWaitForTimer
 @ stdcall WaitForThreadpoolWaitCallbacks(ptr long) ntdll.TpWaitForWait
 @ stdcall WaitForThreadpoolWorkCallbacks(ptr long) ntdll.TpWaitForWork
diff --git a/dlls/kernelbase/kernelbase.spec b/dlls/kernelbase/kernelbase.spec
index d74f65c8f11..9aa0613ea5f 100644
--- a/dlls/kernelbase/kernelbase.spec
+++ b/dlls/kernelbase/kernelbase.spec
@@ -105,7 +105,7 @@
 @ stdcall CancelIo(long)
 @ stdcall CancelIoEx(long ptr)
 @ stdcall CancelSynchronousIo(long)
-@ stub CancelThreadpoolIo
+@ stdcall CancelThreadpoolIo(ptr) ntdll.TpCancelAsyncIoOperation
 @ stdcall CancelWaitableTimer(long)
 # @ stub CeipIsOptedIn
 @ stdcall ChangeTimerQueueTimer(ptr ptr long long)
@@ -146,7 +146,7 @@
 @ stdcall CloseThreadpool(ptr) ntdll.TpReleasePool
 @ stdcall CloseThreadpoolCleanupGroup(ptr) ntdll.TpReleaseCleanupGroup
 @ stdcall CloseThreadpoolCleanupGroupMembers(ptr long ptr) ntdll.TpReleaseCleanupGroupMembers
-@ stub CloseThreadpoolIo
+@ stdcall CloseThreadpoolIo(ptr) ntdll.TpReleaseIoCompletion
 @ stdcall CloseThreadpoolTimer(ptr) ntdll.TpReleaseTimer
 @ stdcall CloseThreadpoolWait(ptr) ntdll.TpReleaseWait
 @ stdcall CloseThreadpoolWork(ptr) ntdll.TpReleaseWork
@@ -1690,7 +1690,7 @@
 @ stdcall WaitForMultipleObjectsEx(long ptr long long long)
 @ stdcall WaitForSingleObject(long long)
 @ stdcall WaitForSingleObjectEx(long long long)
-@ stub WaitForThreadpoolIoCallbacks
+@ stdcall WaitForThreadpoolIoCallbacks(ptr) ntdll.TpWaitForIoCompletion
 @ stdcall WaitForThreadpoolTimerCallbacks(ptr long) ntdll.TpWaitForTimer
 @ stdcall WaitForThreadpoolWaitCallbacks(ptr long) ntdll.TpWaitForWait
 @ stdcall WaitForThreadpoolWorkCallbacks(ptr long) ntdll.TpWaitForWork