diff --git a/lib/src/main/java/com/otaliastudios/transcoder/ThumbnailerOptions.kt b/lib/src/main/java/com/otaliastudios/transcoder/ThumbnailerOptions.kt
index 713a5910..b92b42c8 100644
--- a/lib/src/main/java/com/otaliastudios/transcoder/ThumbnailerOptions.kt
+++ b/lib/src/main/java/com/otaliastudios/transcoder/ThumbnailerOptions.kt
@@ -101,7 +101,7 @@ class ThumbnailerOptions(
             )
         }
 
-        fun thumbnails(): ThumbnailsEngine? {
+        fun thumbnails(): ThumbnailsEngine {
             return ThumbnailsEngine.thumbnails(build())
         }
     }
diff --git a/lib/src/main/java/com/otaliastudios/transcoder/internal/thumbnails/ThumbnailsEngine.kt b/lib/src/main/java/com/otaliastudios/transcoder/internal/thumbnails/ThumbnailsEngine.kt
index 326d8012..32b123c8 100644
--- a/lib/src/main/java/com/otaliastudios/transcoder/internal/thumbnails/ThumbnailsEngine.kt
+++ b/lib/src/main/java/com/otaliastudios/transcoder/internal/thumbnails/ThumbnailsEngine.kt
@@ -37,15 +37,14 @@ abstract class ThumbnailsEngine {
             }
         }
 
-        var engine: ThumbnailsEngine? = null
         private lateinit var dispatcher: ThumbnailsDispatcher
 
         @JvmStatic
-        fun thumbnails(options: ThumbnailerOptions): ThumbnailsEngine? {
+        fun thumbnails(options: ThumbnailerOptions): ThumbnailsEngine {
             log.i("thumbnails(): called...")
             dispatcher = ThumbnailsDispatcher(options)
 
-            engine = DefaultThumbnailsEngine(
+            val engine = DefaultThumbnailsEngine(
                 dataSources = DataSources(options),
                 rotation = options.rotation,
                 resizer = options.resizer