diff --git a/internal/epub/filters/autorotate.go b/internal/epub/filters/autorotate.go
index cd7e14b..ea12583 100644
--- a/internal/epub/filters/autorotate.go
+++ b/internal/epub/filters/autorotate.go
@@ -7,7 +7,7 @@ import (
 	"github.com/disintegration/gift"
 )
 
-func AutoRotate() *autoRotateFilter {
+func AutoRotate() gift.Filter {
 	return &autoRotateFilter{}
 }
 
diff --git a/internal/epub/filters/crop.go b/internal/epub/filters/crop.go
index 140dbc0..a45cb21 100644
--- a/internal/epub/filters/crop.go
+++ b/internal/epub/filters/crop.go
@@ -7,7 +7,7 @@ import (
 	"github.com/disintegration/gift"
 )
 
-func CropSplitDoublePage(right bool) *cropSplitDoublePage {
+func CropSplitDoublePage(right bool) gift.Filter {
 	return &cropSplitDoublePage{right}
 }