diff --git a/crypto/message.go b/crypto/message.go
index ccdb5d3..d6072fe 100644
--- a/crypto/message.go
+++ b/crypto/message.go
@@ -202,7 +202,7 @@ func (msg *PlainMessage) GetBinary() []byte {
 
 // GetString returns the content of the message as a string.
 func (msg *PlainMessage) GetString() string {
-	return strings.ReplaceAll(string(msg.Data), "\r\n", "\n")
+	return sanitizeString(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 4d55cd0..d756dfc 100644
--- a/crypto/mime.go
+++ b/crypto/mime.go
@@ -49,7 +49,8 @@ func (keyRing *KeyRing) DecryptMIMEMessage(
 		callbacks.OnVerified(constants.SIGNATURE_OK)
 	}
 	bodyContent, bodyMimeType := body.GetBody()
-	callbacks.OnBody(bodyContent, bodyMimeType)
+	bodyContentSanitized := sanitizeString(bodyContent)
+	callbacks.OnBody(bodyContentSanitized, bodyMimeType)
 	for i := 0; i < len(attachments); i++ {
 		callbacks.OnAttachment(attachmentHeaders[i], []byte(attachments[i]))
 	}
diff --git a/crypto/sanitize_string.go b/crypto/sanitize_string.go
new file mode 100644
index 0000000..94aa81c
--- /dev/null
+++ b/crypto/sanitize_string.go
@@ -0,0 +1,8 @@
+//go:build !ios
+// +build !ios
+
+package crypto
+
+func sanitizeString(input string) string {
+	return input
+}
diff --git a/crypto/sanitize_string_ios.go b/crypto/sanitize_string_ios.go
new file mode 100644
index 0000000..561414b
--- /dev/null
+++ b/crypto/sanitize_string_ios.go
@@ -0,0 +1,10 @@
+//go:build ios
+// +build ios
+
+package crypto
+
+import "strings"
+
+func sanitizeString(input string) string {
+	return strings.ToValidUTF8(input, "\ufffd")
+}