diff --git a/validator/src/main/java/org/mustangproject/validator/PDFValidator.java b/validator/src/main/java/org/mustangproject/validator/PDFValidator.java
index f8fe6156..d1ba1afc 100644
--- a/validator/src/main/java/org/mustangproject/validator/PDFValidator.java
+++ b/validator/src/main/java/org/mustangproject/validator/PDFValidator.java
@@ -283,6 +283,7 @@ public class PDFValidator extends Validator {
 		final byte[] cibpdfbrewerSignature = "CIB pdf brewer".getBytes(StandardCharsets.UTF_8);
 		final byte[] lexofficeSignature = "lexoffice".getBytes(StandardCharsets.UTF_8);		
 		final byte[] s2IndustriesSignature = "s2industries.ZUGFeRD.PDF".getBytes(StandardCharsets.UTF_8); // https://github.com/stephanstapel/ZUGFeRD-csharp
+		final byte[] factoorSharpSignature = "FactoorSharp".getBytes(StandardCharsets.UTF_8); // https://github.com/S2-Industries/FactoorSharp
 		final byte[] sevdeskSignature = "sevdesk".getBytes(StandardCharsets.UTF_8);
 
 		if (ByteArraySearcher.contains(fileContents, symtraxSignature)) {
@@ -305,6 +306,8 @@ public class PDFValidator extends Validator {
 			Signature = "Lexware office";
 		} else if (ByteArraySearcher.contains(fileContents, s2IndustriesSignature)) {
 			Signature = "ZUGFeRD.PDF-csharp";
+		} else if (ByteArraySearcher.contains(fileContents, factoorSharpSignature)) {
+			Signature = "FactoorSharp";
 		} else if (ByteArraySearcher.contains(fileContents, sevdeskSignature)) {
 			Signature = "sevdesk";
 		}