diff --git a/codec/std/tx.go b/codec/std/tx.go
index eca3553f30..8305c75177 100644
--- a/codec/std/tx.go
+++ b/codec/std/tx.go
@@ -122,9 +122,11 @@ func (tx Transaction) GetSignatures() []sdk.Signature {
 // SetSignatures sets the transaction's signatures. It will overwrite any
 // existing signatures set.
 func (tx *Transaction) SetSignatures(sdkSigs ...sdk.Signature) {
-	sigs := make([]auth.StdSignature, len(tx.Signatures))
+	sigs := make([]auth.StdSignature, len(sdkSigs))
 	for i, sig := range sdkSigs {
-		sigs[i] = auth.NewStdSignature(sig.GetPubKey(), sig.GetSignature())
+		if sig != nil {
+			sigs[i] = auth.NewStdSignature(sig.GetPubKey(), sig.GetSignature())
+		}
 	}
 
 	tx.Signatures = sigs
diff --git a/x/auth/types/stdtx.go b/x/auth/types/stdtx.go
index 12e4aecd0b..04e9ec1fdd 100644
--- a/x/auth/types/stdtx.go
+++ b/x/auth/types/stdtx.go
@@ -59,7 +59,12 @@ func (fee StdFee) GasPrices() sdk.DecCoins {
 }
 
 func NewStdSignature(pk crypto.PubKey, sig []byte) StdSignature {
-	return StdSignature{PubKey: pk.Bytes(), Signature: sig}
+	var pkBz []byte
+	if pk != nil {
+		pkBz = pk.Bytes()
+	}
+
+	return StdSignature{PubKey: pkBz, Signature: sig}
 }
 
 // GetSignature returns the raw signature bytes.