diff --git a/src/UglyToad.PdfPig/Encryption/EncryptionHandler.cs b/src/UglyToad.PdfPig/Encryption/EncryptionHandler.cs
index fb9757f8..f02f1c6d 100644
--- a/src/UglyToad.PdfPig/Encryption/EncryptionHandler.cs
+++ b/src/UglyToad.PdfPig/Encryption/EncryptionHandler.cs
@@ -64,6 +64,9 @@
                     case HexToken hex:
                         documentIdBytes = hex.Bytes.ToArray();
                         break;
+                    case StringToken str:
+                        documentIdBytes = str.GetBytes();
+                        break;
                     default:
                         documentIdBytes = OtherEncodings.StringAsLatin1Bytes(token.Data);
                         break;