diff --git a/ethers/signer.nim b/ethers/signer.nim
index 16e1180..5cd577f 100644
--- a/ethers/signer.nim
+++ b/ethers/signer.nim
@@ -139,6 +139,8 @@ method populateTransaction*(
     if transaction.gasLimit.isNone:
       populated.gasLimit = some(await signer.estimateGas(populated, BlockTag.pending))
 
+  doAssert transaction.nonce.isSome, "nonce not populated!"
+
   return populated
 
 method cancelTransaction*(