diff --git a/eth_p2p/blockchain_sync.nim b/eth_p2p/blockchain_sync.nim
index 3688b15..495ab3b 100644
--- a/eth_p2p/blockchain_sync.nim
+++ b/eth_p2p/blockchain_sync.nim
@@ -329,10 +329,10 @@ proc onPeerDisconnected(ctx: SyncContext, p: Peer) =
 
 proc startSync(ctx: SyncContext) =
   var po: PeerObserver
-  po.onPeerConnected = proc(p: Peer) =
+  po.onPeerConnected = proc(p: Peer) {.gcsafe.} =
     ctx.onPeerConnected(p)
 
-  po.onPeerDisconnected = proc(p: Peer) =
+  po.onPeerDisconnected = proc(p: Peer) {.gcsafe.} =
     ctx.onPeerDisconnected(p)
 
   ctx.peerPool.addObserver(ctx, po)
diff --git a/eth_p2p/rlpx_protocols/les_protocol.nim b/eth_p2p/rlpx_protocols/les_protocol.nim
index 7b593a4..c8a9640 100644
--- a/eth_p2p/rlpx_protocols/les_protocol.nim
+++ b/eth_p2p/rlpx_protocols/les_protocol.nim
@@ -75,7 +75,7 @@ const
   keyAnnounceType = "announceType"
   keyAnnounceSignature = "sign"
 
-proc initProtocolState(network: LesNetwork, node: EthereumNode) =
+proc initProtocolState(network: LesNetwork, node: EthereumNode) {.gcsafe.} =
   network.peers = initSet[LesPeer]()
 
 proc addPeer(network: LesNetwork, peer: LesPeer) =