diff --git a/sign/sign.go b/sign/sign.go
index a6d5c5d..ea37a81 100644
--- a/sign/sign.go
+++ b/sign/sign.go
@@ -201,7 +201,7 @@ func (context *SignContext) SignPDF() error {
 	// Add estimated size for TSA.
 	// We can't kow actual size of TSA until after signing.
 	if context.SignData.TSA.URL != "" {
-		context.SignatureMaxLength += uint32(hex.EncodedLen(5000))
+		context.SignatureMaxLength += uint32(hex.EncodedLen(4000))
 	}
 
 	// Fetch revocation data before adding signature placeholder.
diff --git a/sign/sign_test.go b/sign/sign_test.go
index c4bc78b..5570151 100644
--- a/sign/sign_test.go
+++ b/sign/sign_test.go
@@ -287,7 +287,7 @@ func BenchmarkSignPDF(b *testing.B) {
 	}
 
 	for n := 0; n < b.N; n++ {
-
+		input_file.Seek(0, 0)
 
 		err = Sign(input_file, ioutil.Discard, rdr, size, SignData{
 			Signature: SignDataSignature{