diff --git a/src/fold.c b/src/fold.c
index 2cd4dcd..3353cc5 100644
--- a/src/fold.c
+++ b/src/fold.c
@@ -1492,6 +1492,9 @@
 // foldMarkAdjust() {{{2
 /*
  * Update line numbers of folds for inserted/deleted lines.
+ *
+ * We are adjusting the folds in the range from line1 til line2,
+ * make sure that line2 does not get smaller than line1
  */
     void
 foldMarkAdjust(
@@ -1505,6 +1508,8 @@
     // lines, set line2 so that only deleted lines have their folds removed.
     if (amount == MAXLNUM && line2 >= line1 && line2 - line1 >= -amount_after)
 	line2 = line1 - amount_after - 1;
+    if (line2 < line1)
+	line2 = line1;
     // If appending a line in Insert mode, it should be included in the fold
     // just above the line.
     if ((State & MODE_INSERT) && amount == (linenr_T)1 && line2 == MAXLNUM)