diff --git a/ethers/provider.nim b/ethers/provider.nim
index 5524dca..97f6fee 100644
--- a/ethers/provider.nim
+++ b/ethers/provider.nim
@@ -59,56 +59,56 @@ type
 const EthersDefaultConfirmations* {.intdefine.} = 12
 const EthersReceiptTimeoutBlks* {.intdefine.} = 50 # in blocks
 
-method getBlockNumber*(provider: Provider): Future[UInt256] {.base.} =
+method getBlockNumber*(provider: Provider): Future[UInt256] {.base, gcsafe.} =
   doAssert false, "not implemented"
 
-method getBlock*(provider: Provider, tag: BlockTag): Future[?Block] {.base.} =
+method getBlock*(provider: Provider, tag: BlockTag): Future[?Block] {.base, gcsafe.} =
   doAssert false, "not implemented"
 
 method call*(provider: Provider,
              tx: Transaction,
-             blockTag = BlockTag.latest): Future[seq[byte]] {.base.} =
+             blockTag = BlockTag.latest): Future[seq[byte]] {.base, gcsafe.} =
   doAssert false, "not implemented"
 
-method getGasPrice*(provider: Provider): Future[UInt256] {.base.} =
+method getGasPrice*(provider: Provider): Future[UInt256] {.base, gcsafe.} =
   doAssert false, "not implemented"
 
 method getTransactionCount*(provider: Provider,
                             address: Address,
                             blockTag = BlockTag.latest):
-                           Future[UInt256] {.base.} =
+                           Future[UInt256] {.base, gcsafe.} =
   doAssert false, "not implemented"
 
 method getTransactionReceipt*(provider: Provider,
                             txHash: TransactionHash):
-                           Future[?TransactionReceipt] {.base.} =
+                           Future[?TransactionReceipt] {.base, gcsafe.} =
   doAssert false, "not implemented"
 
 method sendTransaction*(provider: Provider,
                         rawTransaction: seq[byte]):
-                       Future[TransactionResponse] {.base.} =
+                       Future[TransactionResponse] {.base, gcsafe.} =
   doAssert false, "not implemented"
 
 method getLogs*(provider: Provider,
-                filter: EventFilter): Future[seq[Log]] {.base.} =
+                filter: EventFilter): Future[seq[Log]] {.base, gcsafe.} =
   doAssert false, "not implemented"
 
 method estimateGas*(provider: Provider,
-                    transaction: Transaction): Future[UInt256] {.base.} =
+                    transaction: Transaction): Future[UInt256] {.base, gcsafe.} =
   doAssert false, "not implemented"
 
-method getChainId*(provider: Provider): Future[UInt256] {.base.} =
+method getChainId*(provider: Provider): Future[UInt256] {.base, gcsafe.} =
   doAssert false, "not implemented"
 
 method subscribe*(provider: Provider,
                   filter: EventFilter,
                   callback: LogHandler):
-                 Future[Subscription] {.base.} =
+                 Future[Subscription] {.base, gcsafe.} =
   doAssert false, "not implemented"
 
 method subscribe*(provider: Provider,
                   callback: BlockHandler):
-                 Future[Subscription] {.base.} =
+                 Future[Subscription] {.base, gcsafe.} =
   doAssert false, "not implemented"
 
 method unsubscribe*(subscription: Subscription) {.base, async.} =
diff --git a/ethers/signer.nim b/ethers/signer.nim
index 3405056..4208c6d 100644
--- a/ethers/signer.nim
+++ b/ethers/signer.nim
@@ -9,10 +9,10 @@ type SignerError* = object of EthersError
 template raiseSignerError(message: string) =
   raise newException(SignerError, message)
 
-method provider*(signer: Signer): Provider {.base.} =
+method provider*(signer: Signer): Provider {.base, gcsafe.} =
   doAssert false, "not implemented"
 
-method getAddress*(signer: Signer): Future[Address] {.base.} =
+method getAddress*(signer: Signer): Future[Address] {.base, gcsafe.} =
   doAssert false, "not implemented"
 
 method signMessage*(signer: Signer,
@@ -23,7 +23,7 @@ method sendTransaction*(signer: Signer,
                         transaction: Transaction): Future[TransactionResponse] {.base, async.} =
   doAssert false, "not implemented"
 
-method getGasPrice*(signer: Signer): Future[UInt256] {.base.} =
+method getGasPrice*(signer: Signer): Future[UInt256] {.base, gcsafe.} =
   signer.provider.getGasPrice()
 
 method getTransactionCount*(signer: Signer,
@@ -38,7 +38,7 @@ method estimateGas*(signer: Signer,
   transaction.sender = some(await signer.getAddress)
   return await signer.provider.estimateGas(transaction)
 
-method getChainId*(signer: Signer): Future[UInt256] {.base.} =
+method getChainId*(signer: Signer): Future[UInt256] {.base, gcsafe.} =
   signer.provider.getChainId()
 
 method populateTransaction*(signer: Signer,