diff --git a/crypto/ecies/ecies.go b/crypto/ecies/ecies.go
index 378d764a19..c99756a65b 100644
--- a/crypto/ecies/ecies.go
+++ b/crypto/ecies/ecies.go
@@ -254,9 +254,12 @@ func Encrypt(rand io.Reader, pub *PublicKey, m, s1, s2 []byte) (ct []byte, err e
 	Ke, Km := deriveKeys(hash, z, s1, params.KeyLen)
 
 	em, err := symEncrypt(rand, params, Ke, m)
-	if err != nil || len(em) <= params.BlockSize {
+	if err != nil {
 		return nil, err
 	}
+	if len(em) <= params.BlockSize {
+		return nil, ErrInvalidMessage
+	}
 
 	d := messageTag(params.Hash, Km, em, s2)