diff --git a/services/thumbnails/README.md b/services/thumbnails/README.md
index 2e38a46e4a0..345d67274ab 100644
--- a/services/thumbnails/README.md
+++ b/services/thumbnails/README.md
@@ -53,10 +53,10 @@ Returned: 15x10
 
 Image generation can be configured by defining different processors, following processors are available:
 
-* resize
-* fit
-* fill
-* thumbnail
+*   resize
+*   fit
+*   fill
+*   thumbnail
 
 to apply one of those, a query parameter has to be added to the request, e.g. `?processor=fit`
 
diff --git a/services/thumbnails/pkg/thumbnail/generator.go b/services/thumbnails/pkg/thumbnail/generator.go
index 984087ff89b..e8d967c4eb9 100644
--- a/services/thumbnails/pkg/thumbnail/generator.go
+++ b/services/thumbnails/pkg/thumbnail/generator.go
@@ -18,7 +18,7 @@ type Generator interface {
 // SimpleGenerator is the default image generator and is used for all image types expect gif.
 type SimpleGenerator struct{}
 
-// Generate creates the image version based on the processor.
+// Generate generates a alternative image version.
 func (g SimpleGenerator) Generate(size image.Rectangle, img interface{}, processor Processor) (interface{}, error) {
 	m, ok := img.(image.Image)
 	if !ok {
@@ -31,6 +31,7 @@ func (g SimpleGenerator) Generate(size image.Rectangle, img interface{}, process
 // GifGenerator is used to create a web friendly version of the provided gif image.
 type GifGenerator struct{}
 
+// Generate generates a alternative gif version.
 func (g GifGenerator) Generate(size image.Rectangle, img interface{}, processor Processor) (interface{}, error) {
 	// Code inspired by https://github.com/willnorris/gifresize/blob/db93a7e1dcb1c279f7eeb99cc6d90b9e2e23e871/gifresize.go
 
diff --git a/services/thumbnails/pkg/thumbnail/processor.go b/services/thumbnails/pkg/thumbnail/processor.go
index 5101518e10d..3782fac4fce 100644
--- a/services/thumbnails/pkg/thumbnail/processor.go
+++ b/services/thumbnails/pkg/thumbnail/processor.go
@@ -28,7 +28,7 @@ func (p DefinableProcessor) Process(img image.Image, width, height int, filter i
 }
 
 // ProcessorFor returns a matching Processor
-func ProcessorFor(id, fileType string) (Processor, error) {
+func ProcessorFor(id, fileType string) (DefinableProcessor, error) {
 	switch strings.ToLower(id) {
 	case "fit":
 		return DefinableProcessor{Slug: strings.ToLower(id), Converter: imaging.Fit}, nil