diff --git a/source/blender/blenloader/intern/writefile.c b/source/blender/blenloader/intern/writefile.c
index 3dc1fed46c8..bf82a4fa551 100644
--- a/source/blender/blenloader/intern/writefile.c
+++ b/source/blender/blenloader/intern/writefile.c
@@ -2057,7 +2057,8 @@ static void write_lattices(WriteData *wd, ListBase *idbase)
 
 static void write_previews(WriteData *wd, PreviewImage *prv)
 {
-	if (prv) {
+	/* Never write previews in undo steps! */
+	if (prv && !wd->current) {
 		short w = prv->w[1];
 		short h = prv->h[1];
 		unsigned int *rect = prv->rect[1];