diff --git a/runtime/doc/eval.txt b/runtime/doc/eval.txt
index ffe5ea9..8bb990a 100644
--- a/runtime/doc/eval.txt
+++ b/runtime/doc/eval.txt
@@ -2681,7 +2681,11 @@
 		Examples: >
 			:echo sort(extend(mylist, [7, 5]))
 			:call extend(mylist, [2, 3], 1)
-<		Use |add()| to concatenate one item to a list.	To concatenate
+<		When {expr1} is the same List as {expr2} then the number of
+		items copied is equal to the original length of the List.
+		E.g., when {expr3} is 1 you get N new copies of the first item
+		(where N is the original length of the List).
+		Use |add()| to concatenate one item to a list.	To concatenate
 		two lists into a new list use the + operator: >
 			:let newlist = [1, 2, 3] + [4, 5]
 <
diff --git a/src/eval.c b/src/eval.c
index cb548d3..5802a08 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -6231,8 +6231,11 @@
     listitem_T	*bef;
 {
     listitem_T	*item;
+    int		todo = l2->lv_len;
 
-    for (item = l2->lv_first; item != NULL; item = item->li_next)
+    /* We also quit the loop when we have inserted the original item count of
+     * the list, avoid a hang when we extend a list with itself. */
+    for (item = l2->lv_first; item != NULL && --todo >= 0; item = item->li_next)
 	if (list_insert_tv(l1, &item->li_tv, bef) == FAIL)
 	    return FAIL;
     return OK;
diff --git a/src/version.c b/src/version.c
index 21d7b14..c8565c4 100644
--- a/src/version.c
+++ b/src/version.c
@@ -677,6 +677,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1,
+/**/
     0
 };