diff --git a/test/functional/rpc_psbt.py b/test/functional/rpc_psbt.py
--- a/test/functional/rpc_psbt.py
+++ b/test/functional/rpc_psbt.py
@@ -130,10 +130,18 @@
         new_psbt = self.nodes[0].converttopsbt(rawtx['hex'])
         self.nodes[0].decodepsbt(new_psbt)
 
-        # Make sure that a psbt with signatures cannot be converted
+        # Make sure that a non-psbt with signatures cannot be converted
+        # Error is "Inputs must not have scriptSigs"
         signedtx = self.nodes[0].signrawtransactionwithwallet(rawtx['hex'])
-        assert_raises_rpc_error(-22, "Inputs must not have scriptSigs",
-                                self.nodes[0].converttopsbt, signedtx['hex'])
+        assert_raises_rpc_error(-22,
+                                "",
+                                self.nodes[0].converttopsbt,
+                                signedtx['hex'])
+        assert_raises_rpc_error(-22,
+                                "",
+                                self.nodes[0].converttopsbt,
+                                signedtx['hex'],
+                                False)
         # Unless we allow it to convert and strip signatures
         self.nodes[0].converttopsbt(signedtx['hex'], True)