diff --git a/crypto/message.go b/crypto/message.go
index 661f71c..435f3ad 100644
--- a/crypto/message.go
+++ b/crypto/message.go
@@ -9,6 +9,7 @@ import (
 	"io/ioutil"
 	"regexp"
 	"runtime"
+	"strings"
 
 	"github.com/ProtonMail/gopenpgp/v2/armor"
 	"github.com/ProtonMail/gopenpgp/v2/constants"
@@ -86,7 +87,7 @@ func NewPlainMessageFromFile(data []byte, filename string, time uint32) *PlainMe
 // ready for encryption, signature, or verification from an unencrypted string.
 func NewPlainMessageFromString(text string) *PlainMessage {
 	return &PlainMessage{
-		Data:     []byte(text),
+		Data:     []byte(strings.ReplaceAll(strings.ReplaceAll(text, "\r\n", "\n"), "\n", "\r\n")),
 		TextType: true,
 		time:     uint32(GetUnixTime()),
 	}
@@ -195,7 +196,7 @@ func (msg *PlainMessage) GetBinary() []byte {
 
 // GetString returns the content of the message as a string.
 func (msg *PlainMessage) GetString() string {
-	return string(msg.Data)
+	return strings.ReplaceAll(string(msg.Data), "\r\n", "\n")
 }
 
 // GetBase64 returns the base-64 encoded binary content of the message as a
diff --git a/crypto/mime.go b/crypto/mime.go
index 9210252..81c2053 100644
--- a/crypto/mime.go
+++ b/crypto/mime.go
@@ -33,7 +33,7 @@ func (keyRing *KeyRing) DecryptMIMEMessage(
 		return
 	}
 
-	body, attachments, attachmentHeaders, err := parseMIME(decryptedMessage.GetString(), verifyKey)
+	body, attachments, attachmentHeaders, err := parseMIME(string(decryptedMessage.GetBinary()), verifyKey)
 	if err != nil {
 		callbacks.OnError(err)
 		return
diff --git a/crypto/signature_test.go b/crypto/signature_test.go
index c69869e..322d73f 100644
--- a/crypto/signature_test.go
+++ b/crypto/signature_test.go
@@ -51,7 +51,8 @@ func TestVerifyTextDetachedSigWrong(t *testing.T) {
 func TestSignBinDetached(t *testing.T) {
 	var err error
 
-	binSignature, err = keyRingTestPrivate.SignDetached(NewPlainMessage([]byte(signedPlainText)))
+	message = NewPlainMessage([]byte(signedPlainText))
+	binSignature, err = keyRingTestPrivate.SignDetached(message)
 	if err != nil {
 		t.Fatal("Cannot generate signature:", err)
 	}
diff --git a/helper/cleartext.go b/helper/cleartext.go
index 9d477f5..6ddd945 100644
--- a/helper/cleartext.go
+++ b/helper/cleartext.go
@@ -1,8 +1,6 @@
 package helper
 
 import (
-	"strings"
-
 	"github.com/ProtonMail/gopenpgp/v2/crypto"
 	"github.com/ProtonMail/gopenpgp/v2/internal"
 )
@@ -50,7 +48,7 @@ func VerifyCleartextMessageArmored(publicKey, armored string, verifyTime int64)
 // SignCleartextMessage signs text given a private keyring, canonicalizes and
 // trims the newlines, and returns the PGP-compliant special armoring.
 func SignCleartextMessage(keyRing *crypto.KeyRing, text string) (string, error) {
-	text = canonicalizeAndTrim(text)
+	text = internal.TrimWhitespace(text)
 	message := crypto.NewPlainMessageFromString(text)
 
 	signature, err := keyRing.SignDetached(message)
@@ -79,12 +77,3 @@ func VerifyCleartextMessage(keyRing *crypto.KeyRing, armored string, verifyTime
 
 	return message.GetString(), nil
 }
-
-// ----- INTERNAL FUNCTIONS -----
-
-// canonicalizeAndTrim alters a string canonicalizing and trimming the newlines.
-func canonicalizeAndTrim(text string) string {
-	text = internal.TrimNewlines(text)
-	text = strings.ReplaceAll(strings.ReplaceAll(text, "\r\n", "\n"), "\n", "\r\n")
-	return text
-}
diff --git a/helper/cleartext_test.go b/helper/cleartext_test.go
index 5d8cf89..8452afb 100644
--- a/helper/cleartext_test.go
+++ b/helper/cleartext_test.go
@@ -2,13 +2,16 @@ package helper
 
 import (
 	"regexp"
+	"strings"
 	"testing"
 
 	"github.com/ProtonMail/gopenpgp/v2/crypto"
+	"github.com/ProtonMail/gopenpgp/v2/internal"
 	"github.com/stretchr/testify/assert"
 )
 
-const signedPlainText = "Signed message\n"
+const inputPlainText = "  Signed message\n  \n  "
+const signedPlainText = "  Signed message\n\n"
 
 var signedMessageTest = regexp.MustCompile(
 	"(?s)^-----BEGIN PGP SIGNED MESSAGE-----.*-----BEGIN PGP SIGNATURE-----.*-----END PGP SIGNATURE-----$")
@@ -18,7 +21,7 @@ func TestSignClearText(t *testing.T) {
 	armored, err := SignCleartextMessageArmored(
 		readTestFile("keyring_privateKey", false),
 		testMailboxPassword,
-		signedPlainText,
+		inputPlainText,
 	)
 
 	if err != nil {
@@ -36,11 +39,17 @@ func TestSignClearText(t *testing.T) {
 		t.Fatal("Cannot verify message:", err)
 	}
 
-	assert.Exactly(t, canonicalizeAndTrim(signedPlainText), verified)
+	assert.Exactly(t, signedPlainText, verified)
+
+	clearTextMessage, err := crypto.NewClearTextMessageFromArmored(armored)
+	if err != nil {
+		t.Fatal("Cannot parse message:", err)
+	}
+	assert.Exactly(t, canonicalizeAndTrim(inputPlainText), string(clearTextMessage.GetBinary()))
 }
 
-func TestMessageCanonicalizeAndTrim(t *testing.T) {
-	text := "Hi  \ntest!\r\n\n"
-	canon := canonicalizeAndTrim(text)
-	assert.Exactly(t, "Hi\r\ntest!\r\n\r\n", canon)
+func canonicalizeAndTrim(text string) string {
+	text = internal.TrimWhitespace(text)
+	text = strings.ReplaceAll(strings.ReplaceAll(text, "\r\n", "\n"), "\n", "\r\n")
+	return text
 }
diff --git a/internal/common.go b/internal/common.go
index d329729..e2c69ad 100644
--- a/internal/common.go
+++ b/internal/common.go
@@ -7,9 +7,9 @@ import (
 	"github.com/ProtonMail/gopenpgp/v2/constants"
 )
 
-// TrimNewlines removes whitespace from the end of each line of the input
+// TrimWhitespace removes whitespace from the end of each line of the input
 // string.
-func TrimNewlines(input string) string {
+func TrimWhitespace(input string) string {
 	var re = regexp.MustCompile(`(?m)[ \t]*$`)
 	return re.ReplaceAllString(input, "")
 }