diff --git a/curve/ecgfp5/scalar_field.go b/curve/ecgfp5/scalar_field.go
index 6b977e8..05ada73 100644
--- a/curve/ecgfp5/scalar_field.go
+++ b/curve/ecgfp5/scalar_field.go
@@ -5,6 +5,7 @@ import (
 	"encoding/binary"
 	"math/big"
 
+	"github.com/elliottech/poseidon_crypto/field/goldilocks"
 	gFp5 "github.com/elliottech/poseidon_crypto/field/goldilocks_quintic_extension"
 	. "github.com/elliottech/poseidon_crypto/int"
 )
@@ -13,6 +14,18 @@ import (
 // p = 1067993516717146951041484916571792702745057740581727230159139685185762082554198619328292418486241
 type ECgFp5Scalar [5]uint64
 
+func (s ECgFp5Scalar) IsCanonical() bool {
+	for _, elem := range s {
+		if elem >= goldilocks.ORDER {
+			return false
+		}
+	}
+	if ToNonCanonicalBigInt(s).Cmp(ORDER) >= 0 {
+		return false
+	}
+	return true
+}
+
 var (
 	ORDER, _ = new(big.Int).SetString("1067993516717146951041484916571792702745057740581727230159139685185762082554198619328292418486241", 10)
 	ZERO     = ECgFp5Scalar{}
diff --git a/signature/schnorr/schnorr.go b/signature/schnorr/schnorr.go
index 8b3513c..910522d 100644
--- a/signature/schnorr/schnorr.go
+++ b/signature/schnorr/schnorr.go
@@ -15,6 +15,10 @@ type Signature struct {
 	E curve.ECgFp5Scalar
 }
 
+func (s Signature) IsCanonical() bool {
+	return s.E.IsCanonical() && s.S.IsCanonical()
+}
+
 var ZERO_SIG = Signature{
 	S: curve.ZERO,
 	E: curve.ZERO,
@@ -102,6 +106,10 @@ func Validate(pubKey, hashedMsg, sig []byte) error {
 }
 
 func IsSchnorrSignatureValid(pubKey, hashedMsg gFp5.Element, sig Signature) bool {
+	if !sig.IsCanonical() {
+		return false
+	}
+
 	pubKeyWs, ok := curve.DecodeFp5AsWeierstrass(pubKey)
 	if !ok {
 		return false