diff --git a/src/components/converter/converter-steps/upload-step/upload-step.tsx b/src/components/converter/converter-steps/upload-step/upload-step.tsx
index c4c9b49..e9eb3b3 100644
--- a/src/components/converter/converter-steps/upload-step/upload-step.tsx
+++ b/src/components/converter/converter-steps/upload-step/upload-step.tsx
@@ -73,8 +73,15 @@ const UploadStep = memo(function UploadStepComponent(
 
   const onSelectedFormatChange = useCallback(
     (value: (string | number)[]) => {
-      setFormat(value[1] as string)
-      props.updateSelectedExtension(value[1] as string)
+      const result = value[1] as string
+
+      if (!result) {
+        console.warn('Could not read selected format.')
+        return
+      }
+
+      setFormat(result)
+      props.updateSelectedExtension(result)
     },
     [props],
   )
diff --git a/src/model/format.ts b/src/model/format.ts
index 9b8c08a..276f95e 100644
--- a/src/model/format.ts
+++ b/src/model/format.ts
@@ -1,6 +1,7 @@
-/** Defines a format */
+/** Category of a Format */
 type FormatCategory = 'Image' | 'Audio' | 'Video' | 'File'
 
+/** Defines a format */
 export type Format = {
   /** Name o the format */
   name: string