diff --git a/src/Data/QRCodeDataException.php b/src/Data/QRCodeDataException.php
index b260e4942..331554073 100644
--- a/src/Data/QRCodeDataException.php
+++ b/src/Data/QRCodeDataException.php
@@ -12,4 +12,4 @@ namespace chillerlan\QRCode\Data;
 
 use chillerlan\QRCode\QRCodeException;
 
-class QRCodeDataException extends QRCodeException{}
+final class QRCodeDataException extends QRCodeException{}
diff --git a/src/Decoder/QRCodeDecoderException.php b/src/Decoder/QRCodeDecoderException.php
index 8fb67d801..4691b0963 100644
--- a/src/Decoder/QRCodeDecoderException.php
+++ b/src/Decoder/QRCodeDecoderException.php
@@ -12,4 +12,4 @@ namespace chillerlan\QRCode\Decoder;
 
 use chillerlan\QRCode\QRCodeException;
 
-class QRCodeDecoderException extends QRCodeException{}
+final class QRCodeDecoderException extends QRCodeException{}
diff --git a/src/Detector/QRCodeDetectorException.php b/src/Detector/QRCodeDetectorException.php
index 87834ebcb..1031e43b3 100644
--- a/src/Detector/QRCodeDetectorException.php
+++ b/src/Detector/QRCodeDetectorException.php
@@ -12,4 +12,4 @@ namespace chillerlan\QRCode\Detector;
 
 use chillerlan\QRCode\QRCodeException;
 
-class QRCodeDetectorException extends QRCodeException{}
+final class QRCodeDetectorException extends QRCodeException{}
diff --git a/src/Output/QRCodeOutputException.php b/src/Output/QRCodeOutputException.php
index 62d971877..a0c20c453 100644
--- a/src/Output/QRCodeOutputException.php
+++ b/src/Output/QRCodeOutputException.php
@@ -12,4 +12,4 @@ namespace chillerlan\QRCode\Output;
 
 use chillerlan\QRCode\QRCodeException;
 
-class QRCodeOutputException extends QRCodeException{}
+final class QRCodeOutputException extends QRCodeException{}