1 files changed, 1 insertions, 0 deletions
diff --git a/macosx/HBController.m b/macosx/HBController.m
index 79c2638e7..c489ae2fb 100644
--- a/macosx/HBController.m
+++ b/macosx/HBController.m
@@ -859,6 +859,7 @@ static void *HBControllerQueueCoreContext = &HBControllerQueueCoreContext;
     }
     else
     {
+        [fPreviewController.generator invalidate];
         fPreviewController.generator = nil;
         self.summaryController.generator = nil;
     }