diff --git a/docs/notary.md b/docs/notary.md
index 586a63341..ad5f9e14d 100644
--- a/docs/notary.md
+++ b/docs/notary.md
@@ -376,8 +376,9 @@ the steps to create a signature request:
 9. Construct the list of main transactions witnesses (that will be `Scripts`
    transaction field). Use the following rules:
    - Contract-based witness should have `Invocation` script that pushes arguments
-     on stack (it may be empty) and empty `Verification` script. Currently, **only
-     empty** `Invocation` scripts are supported for contract-based witnesses.
+     on stack (it may be empty) and empty `Verification` script. If multiple notary
+     requests provide different `Invocation` scripts then the first one will be used
+     to construct contract-based witness.
    - **Notary contract witness** (which is also a contract-based witness) should
      have empty `Verification` script. `Invocation` script should be of the form
      [opcode.PUSHDATA1, 64, make([]byte, 64)...], i.e. to be a placeholder for
diff --git a/pkg/services/notary/notary.go b/pkg/services/notary/notary.go
index 7b4f15fba..af9b77b0a 100644
--- a/pkg/services/notary/notary.go
+++ b/pkg/services/notary/notary.go
@@ -220,12 +220,18 @@ func (n *Notary) OnNewRequest(payload *payload.P2PNotaryRequest) {
 	}
 	mainHash := hash.NetSha256(uint32(n.Network), r.main).BytesBE()
 	for i, w := range payload.MainTransaction.Scripts {
-		if r.witnessInfo[i].typ == Contract || // check that we need to fill that witness
-			len(w.InvocationScript) == 0 || // check that signature for this witness was provided
-			r.witnessInfo[i].nSigsLeft == 0 { // check that signature wasn't yet added (consider receiving the same payload multiple times)
+		if len(w.InvocationScript) == 0 || // check that signature for this witness was provided
+			(r.witnessInfo[i].nSigsLeft == 0 && r.witnessInfo[i].typ != Contract) { // check that signature wasn't yet added (consider receiving the same payload multiple times)
 			continue
 		}
 		switch r.witnessInfo[i].typ {
+		case Contract:
+			// Need to check even if r.main.Scripts[i].InvocationScript is already filled in.
+			err := n.Config.Chain.VerifyWitness(r.main.Signers[i].Account, r.main, &w, n.Config.Chain.GetPolicer().GetMaxVerificationGAS())
+			if err != nil {
+				continue
+			}
+			r.main.Scripts[i].InvocationScript = w.InvocationScript
 		case Signature:
 			if r.witnessInfo[i].pubs[0].Verify(w.InvocationScript[2:], mainHash) {
 				r.main.Scripts[i] = w