diff --git a/src/quickfix.c b/src/quickfix.c
index ce21661..6de55f7 100644
--- a/src/quickfix.c
+++ b/src/quickfix.c
@@ -4881,7 +4881,9 @@
 	/* Use the specified quickfix/location list */
 	if (di->di_tv.v_type == VAR_NUMBER)
 	{
-	    qf_idx = di->di_tv.vval.v_number - 1;
+	    /* for zero use the current list */
+	    if (di->di_tv.vval.v_number != 0)
+		qf_idx = di->di_tv.vval.v_number - 1;
 	    if (qf_idx < 0 || qf_idx >= qi->qf_listcount)
 		return FAIL;
 	}
@@ -4912,11 +4914,11 @@
     if ((di = dict_find(what, (char_u *)"context", -1)) != NULL)
     {
 	typval_T	*ctx;
-	free_tv(qi->qf_lists[qi->qf_curlist].qf_ctx);
+	free_tv(qi->qf_lists[qf_idx].qf_ctx);
 	ctx =  alloc_tv();
 	if (ctx != NULL)
 	    copy_tv(&di->di_tv, ctx);
-	qi->qf_lists[qi->qf_curlist].qf_ctx = ctx;
+	qi->qf_lists[qf_idx].qf_ctx = ctx;
     }
 
     return retval;
diff --git a/src/testdir/test_quickfix.vim b/src/testdir/test_quickfix.vim
index f1fd3c9..51f6a6f 100644
--- a/src/testdir/test_quickfix.vim
+++ b/src/testdir/test_quickfix.vim
@@ -1804,6 +1804,37 @@
 	call setloclist(0, [], 'f')
 	call assert_equal({}, getloclist(0, {'context':1}))
     endif
+
+    " Test for changing the context of previous quickfix lists
+    call g:Xsetlist([], 'f')
+    Xexpr "One"
+    Xexpr "Two"
+    Xexpr "Three"
+    call g:Xsetlist([], ' ', {'context' : [1], 'nr' : 1})
+    call g:Xsetlist([], ' ', {'context' : [2], 'nr' : 2})
+    " Also, check for setting the context using quickfix list number zero.
+    call g:Xsetlist([], ' ', {'context' : [3], 'nr' : 0})
+    call test_garbagecollect_now()
+    let l = g:Xgetlist({'nr' : 1, 'context' : 1})
+    call assert_equal([1], l.context)
+    let l = g:Xgetlist({'nr' : 2, 'context' : 1})
+    call assert_equal([2], l.context)
+    let l = g:Xgetlist({'nr' : 3, 'context' : 1})
+    call assert_equal([3], l.context)
+
+    " Test for changing the context through reference and for garbage
+    " collection of quickfix context
+    let l = ["red"]
+    call g:Xsetlist([], ' ', {'context' : l})
+    call add(l, "blue")
+    let x = g:Xgetlist({'context' : 1})
+    call add(x.context, "green")
+    call assert_equal(["red", "blue", "green"], l)
+    call assert_equal(["red", "blue", "green"], x.context)
+    unlet l
+    call test_garbagecollect_now()
+    let m = g:Xgetlist({'context' : 1})
+    call assert_equal(["red", "blue", "green"], m.context)
 endfunc
 
 func Test_qf_property()
@@ -2073,3 +2104,19 @@
   call XfreeTests('c')
   call XfreeTests('l')
 endfunc
+
+" Test for buffer overflow when parsing lines and adding new entries to
+" the quickfix list.
+func Test_bufoverflow()
+  set efm=%f:%l:%m
+  cgetexpr ['File1:100:' . repeat('x', 1025)]
+
+  set efm=%+GCompiler:\ %.%#,%f:%l:%m
+  cgetexpr ['Compiler: ' . repeat('a', 1015), 'File1:10:Hello World']
+
+  set efm=%DEntering\ directory\ %f,%f:%l:%m
+  cgetexpr ['Entering directory ' . repeat('a', 1006),
+	      \ 'File1:10:Hello World']
+  set efm&vim
+endfunc
+
diff --git a/src/version.c b/src/version.c
index 2c5aa06..0daa349 100644
--- a/src/version.c
+++ b/src/version.c
@@ -765,6 +765,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    606,
+/**/
     605,
 /**/
     604,