diff --git a/gcs/builder/builder.go b/gcs/builder/builder.go
index 63afad3..71bb69f 100644
--- a/gcs/builder/builder.go
+++ b/gcs/builder/builder.go
@@ -328,7 +328,9 @@ func BuildExtFilter(block *wire.MsgBlock) (*gcs.Filter, error) {
 		// Skip the inputs for the coinbase transaction
 		if i != 0 {
 			for _, txIn := range tx.TxIn {
-				b.AddScript(txIn.SignatureScript)
+				if txIn.SignatureScript != nil {
+					b.AddScript(txIn.SignatureScript)
+				}
 			}
 		}
 	}