diff --git a/libp2p/connmanager.nim b/libp2p/connmanager.nim
index f70ca35e7..5d8db58a6 100644
--- a/libp2p/connmanager.nim
+++ b/libp2p/connmanager.nim
@@ -67,7 +67,8 @@ type
     muxed: Table[PeerId, seq[Muxer]]
     connEvents: array[ConnEventKind, OrderedSet[ConnEventHandler]]
     peerEvents: array[PeerEventKind, OrderedSet[PeerEventHandler]]
-    expectedConnectionsOverLimit*: Table[(PeerId, Direction), Future[Muxer]]
+    expectedConnectionsOverLimit*:
+      Table[(PeerId, Direction), Future[Muxer].Raising([CancelledError])]
     peerStore*: PeerStore
 
   ConnectionSlot* = object
@@ -123,7 +124,9 @@ proc removeConnEventHandler*(
 ) =
   c.connEvents[kind].excl(handler)
 
-proc triggerConnEvent*(c: ConnManager, peerId: PeerId, event: ConnEvent) {.async.} =
+proc triggerConnEvent*(
+    c: ConnManager, peerId: PeerId, event: ConnEvent
+) {.async: (raises: [CancelledError]).} =
   try:
     trace "About to trigger connection events", peer = peerId
     if c.connEvents[event.kind].len() > 0:
@@ -153,7 +156,9 @@ proc removePeerEventHandler*(
 ) =
   c.peerEvents[kind].excl(handler)
 
-proc triggerPeerEvents*(c: ConnManager, peerId: PeerId, event: PeerEvent) {.async.} =
+proc triggerPeerEvents*(
+    c: ConnManager, peerId: PeerId, event: PeerEvent
+) {.async: (raises: [CancelledError]).} =
   trace "About to trigger peer events", peer = peerId
   if c.peerEvents[event.kind].len == 0:
     return
@@ -173,7 +178,7 @@ proc triggerPeerEvents*(c: ConnManager, peerId: PeerId, event: PeerEvent) {.asyn
 
 proc expectConnection*(
     c: ConnManager, p: PeerId, dir: Direction
-): Future[Muxer] {.async.} =
+): Future[Muxer] {.async: (raises: [AlreadyExpectingConnectionError, CancelledError]).} =
   ## Wait for a peer to connect to us. This will bypass the `MaxConnectionsPerPeer`
   let key = (p, dir)
   if key in c.expectedConnectionsOverLimit:
@@ -182,7 +187,7 @@ proc expectConnection*(
       "Already expecting an incoming connection from that peer",
     )
 
-  let future = newFuture[Muxer]()
+  let future = Future[Muxer].Raising([CancelledError]).init()
   c.expectedConnectionsOverLimit[key] = future
 
   try:
@@ -204,7 +209,7 @@ proc contains*(c: ConnManager, muxer: Muxer): bool =
   let conn = muxer.connection
   return muxer in c.muxed.getOrDefault(conn.peerId)
 
-proc closeMuxer(muxer: Muxer) {.async.} =
+proc closeMuxer(muxer: Muxer) {.async: (raises: [CancelledError]).} =
   trace "Cleaning up muxer", m = muxer
 
   await muxer.close()
@@ -215,7 +220,7 @@ proc closeMuxer(muxer: Muxer) {.async.} =
       trace "Exception in close muxer handler", exc = exc.msg
   trace "Cleaned up muxer", m = muxer
 
-proc muxCleanup(c: ConnManager, mux: Muxer) {.async.} =
+proc muxCleanup(c: ConnManager, mux: Muxer) {.async: (raises: [CancelledError]).} =
   try:
     trace "Triggering disconnect events", mux
     let peerId = mux.connection.peerId
@@ -237,7 +242,7 @@ proc muxCleanup(c: ConnManager, mux: Muxer) {.async.} =
     # do not need to propagate CancelledError and should handle other errors
     warn "Unexpected exception peer cleanup handler", mux, msg = exc.msg
 
-proc onClose(c: ConnManager, mux: Muxer) {.async.} =
+proc onClose(c: ConnManager, mux: Muxer) {.async: (raises: [CancelledError]).} =
   ## connection close even handler
   ##
   ## triggers the connections resource cleanup
@@ -321,7 +326,9 @@ proc storeMuxer*(c: ConnManager, muxer: Muxer) {.raises: [CatchableError].} =
 
   trace "Stored muxer", muxer, direction = $muxer.connection.dir, peers = c.muxed.len
 
-proc getIncomingSlot*(c: ConnManager): Future[ConnectionSlot] {.async.} =
+proc getIncomingSlot*(
+    c: ConnManager
+): Future[ConnectionSlot] {.async: (raises: [CancelledError]).} =
   await c.inSema.acquire()
   return ConnectionSlot(connManager: c, direction: In)
 
@@ -354,7 +361,7 @@ proc trackConnection*(cs: ConnectionSlot, conn: Connection) =
     cs.release()
     return
 
-  proc semaphoreMonitor() {.async.} =
+  proc semaphoreMonitor() {.async: (raises: [CancelledError]).} =
     try:
       await conn.join()
     except CatchableError as exc:
@@ -370,14 +377,18 @@ proc trackMuxer*(cs: ConnectionSlot, mux: Muxer) =
     return
   cs.trackConnection(mux.connection)
 
-proc getStream*(c: ConnManager, muxer: Muxer): Future[Connection] {.async.} =
+proc getStream*(
+    c: ConnManager, muxer: Muxer
+): Future[Connection] {.async: (raises: [LPStreamError, MuxerError, CancelledError]).} =
   ## get a muxed stream for the passed muxer
   ##
 
   if not (isNil(muxer)):
     return await muxer.newStream()
 
-proc getStream*(c: ConnManager, peerId: PeerId): Future[Connection] {.async.} =
+proc getStream*(
+    c: ConnManager, peerId: PeerId
+): Future[Connection] {.async: (raises: [LPStreamError, MuxerError, CancelledError]).} =
   ## get a muxed stream for the passed peer from any connection
   ##
 
@@ -385,13 +396,13 @@ proc getStream*(c: ConnManager, peerId: PeerId): Future[Connection] {.async.} =
 
 proc getStream*(
     c: ConnManager, peerId: PeerId, dir: Direction
-): Future[Connection] {.async.} =
+): Future[Connection] {.async: (raises: [LPStreamError, MuxerError, CancelledError]).} =
   ## get a muxed stream for the passed peer from a connection with `dir`
   ##
 
   return await c.getStream(c.selectMuxer(peerId, dir))
 
-proc dropPeer*(c: ConnManager, peerId: PeerId) {.async.} =
+proc dropPeer*(c: ConnManager, peerId: PeerId) {.async: (raises: [CancelledError]).} =
   ## drop connections and cleanup resources for peer
   ##
   trace "Dropping peer", peerId
@@ -402,7 +413,7 @@ proc dropPeer*(c: ConnManager, peerId: PeerId) {.async.} =
 
   trace "Peer dropped", peerId
 
-proc close*(c: ConnManager) {.async.} =
+proc close*(c: ConnManager) {.async: (raises: [CancelledError]).} =
   ## cleanup resources for the connection
   ## manager
   ##
diff --git a/libp2p/utils/semaphore.nim b/libp2p/utils/semaphore.nim
index 6c885ea99..feef60235 100644
--- a/libp2p/utils/semaphore.nim
+++ b/libp2p/utils/semaphore.nim
@@ -20,7 +20,7 @@ logScope:
 type AsyncSemaphore* = ref object of RootObj
   size*: int
   count: int
-  queue: seq[Future[void]]
+  queue: seq[Future[void].Raising([CancelledError])]
 
 proc newAsyncSemaphore*(size: int): AsyncSemaphore =
   AsyncSemaphore(size: size, count: size)
@@ -38,14 +38,14 @@ proc tryAcquire*(s: AsyncSemaphore): bool =
     trace "Acquired slot", available = s.count, queue = s.queue.len
     return true
 
-proc acquire*(s: AsyncSemaphore): Future[void] =
+proc acquire*(s: AsyncSemaphore): Future[void].Raising([CancelledError]) =
   ## Acquire a resource and decrement the resource
   ## counter. If no more resources are available,
   ## the returned future will not complete until
   ## the resource count goes above 0.
   ##
 
-  let fut = newFuture[void]("AsyncSemaphore.acquire")
+  let fut = Future[void].Raising([CancelledError]).init("AsyncSemaphore.acquire")
   if s.tryAcquire():
     fut.complete()
     return fut
diff --git a/tests/testsemaphore.nim b/tests/testsemaphore.nim
index 95e5b9080..a1e6daf93 100644
--- a/tests/testsemaphore.nim
+++ b/tests/testsemaphore.nim
@@ -14,7 +14,7 @@ import chronos
 
 import ../libp2p/utils/semaphore
 
-import ./helpers
+import ./asyncunit
 
 randomize()