diff --git a/src/message.cpp b/src/message.cpp
index 925d6158..f404da31 100644
--- a/src/message.cpp
+++ b/src/message.cpp
@@ -102,6 +102,8 @@ void Message::merge_account_meta(const AccountMeta &account_meta){
 }
 
 void Message::merge_signer(const Variant& signer){
+    ERR_FAIL_COND_EDMSG(Pubkey::is_pubkey(signer), "Pubkey is provided as signing parameter. (Use Keypair or WalletAdapter.)");
+
     for(unsigned int i = 0; i < signers.size(); i++){
         if(Pubkey::bytes_from_variant(signers[i]) == Pubkey::bytes_from_variant(signer)){
             return;
diff --git a/src/transaction.cpp b/src/transaction.cpp
index b64838a7..d511bc4d 100644
--- a/src/transaction.cpp
+++ b/src/transaction.cpp
@@ -487,6 +487,7 @@ PackedByteArray Transaction::serialize_signers(){
 }
 
 Variant Transaction::sign_and_send(){
+    ERR_FAIL_COND_V_EDMSG(Object::cast_to<Message>(message)->get_signers().size() != signatures.size(), Error::ERR_UNCONFIGURED ,"Transaction does not have enough signers.");
     connect("fully_signed", Callable(this, "send_and_disconnect"));
 
     sign();
@@ -525,6 +526,9 @@ void Transaction::blockhash_callback(Dictionary params){
 
 void Transaction::send(){
     ERR_FAIL_COND_EDMSG(!is_inside_tree(), "Transaction node must be added to scene tree.");
+
+    ERR_FAIL_COND_EDMSG(Object::cast_to<Message>(message)->get_signers().size() != signatures.size(), "Transaction does not have enough signers.");
+
     PackedByteArray serialized_bytes = serialize();
 
     Callable pending_blockhash_callback(this, "send");