diff --git a/ethers/providers/jsonrpc/subscriptions.nim b/ethers/providers/jsonrpc/subscriptions.nim
index a7f8855..2bba4d2 100644
--- a/ethers/providers/jsonrpc/subscriptions.nim
+++ b/ethers/providers/jsonrpc/subscriptions.nim
@@ -144,11 +144,12 @@ method subscribeBlocks(subscriptions: WebSocketSubscriptions,
     let res = Block.fromJson(arguments{"result"}).mapFailure(SubscriptionError)
     onBlock(res)
 
-  withLock(subscriptions):
-    convertErrorsToSubscriptionError:
-      let id = await subscriptions.client.eth_subscribe("newHeads")
-      subscriptions.callbacks[id] = callback
-      return id
+  try:
+    withLock(subscriptions):
+      convertErrorsToSubscriptionError:
+        let id = await subscriptions.client.eth_subscribe("newHeads")
+        subscriptions.callbacks[id] = callback
+        return id
   except AsyncLockError as e:
      error "Lock error when trying to subscribe to blocks", err = e.msg
      raise newException(SubscriptionError, "Cannot subscribe to the blocks because of lock error")