diff --git a/rpc/types.go b/rpc/types.go
index 0789a99017..806c9c8a43 100644
--- a/rpc/types.go
+++ b/rpc/types.go
@@ -83,7 +83,11 @@ func newHexData(input interface{}) *hexdata {
 			d.data = input.Bytes()
 		}
 	case *big.Int:
-		d.data = input.Bytes()
+		if input == nil {
+			d.isNil = true
+		} else {
+			d.data = input.Bytes()
+		}
 	case int64:
 		d.data = big.NewInt(input).Bytes()
 	case uint64: