diff --git a/lib/src/main/java/com/otaliastudios/transcoder/internal/CustomSegments.kt b/lib/src/main/java/com/otaliastudios/transcoder/internal/CustomSegments.kt
index c189b9e6..1c1d2435 100644
--- a/lib/src/main/java/com/otaliastudios/transcoder/internal/CustomSegments.kt
+++ b/lib/src/main/java/com/otaliastudios/transcoder/internal/CustomSegments.kt
@@ -52,6 +52,18 @@ class CustomSegments(
         }
     }
 
+    fun releaseSegment(id: String) {
+        val segment = segmentMap[id]
+        segment?.let {
+            it.release()
+            val source = sources[it.type][it.index]
+            if (tracks.active.has(it.type)) {
+                source.releaseTrack(it.type)
+            }
+            segmentMap[id] = null
+        }
+    }
+
     fun release() = destroySegment(true)
 
     private fun tryCreateSegment(id: String): Segment? {
diff --git a/lib/src/main/java/com/otaliastudios/transcoder/internal/thumbnails/DefaultThumbnailsEngine.kt b/lib/src/main/java/com/otaliastudios/transcoder/internal/thumbnails/DefaultThumbnailsEngine.kt
index 93544cad..74ff367c 100644
--- a/lib/src/main/java/com/otaliastudios/transcoder/internal/thumbnails/DefaultThumbnailsEngine.kt
+++ b/lib/src/main/java/com/otaliastudios/transcoder/internal/thumbnails/DefaultThumbnailsEngine.kt
@@ -233,6 +233,7 @@ class DefaultThumbnailsEngine(
     }
 
     override fun removeDataSource(dataSourceId: String) {
+        segments.releaseSegment(dataSourceId)
         dataSources.removeVideoDataSource(dataSourceId)
         tracks.updateTracksInfo()
     }
@@ -285,6 +286,11 @@ class DefaultThumbnailsEngine(
     }
 
     override suspend fun removePosition(source: String, positionUs: Long) {
+        if (positionUs < 0) {
+            stubs.removeAll{
+                it.request.sourceId() == source
+            }
+        }
         if (stubs.firstOrNull()?.request?.sourceId() == source && positionUs == stubs.firstOrNull()?.positionUs) {
             return
         }
@@ -320,6 +326,7 @@ class DefaultThumbnailsEngine(
     }
 
     override fun cleanup() {
+        runCatching { stubs.clear() }
         runCatching { segments.release() }
         runCatching { dataSources.release() }
     }