diff --git a/src/nvim/mark.c b/src/nvim/mark.c
index 1273093d8b..6ce42bb7fe 100644
--- a/src/nvim/mark.c
+++ b/src/nvim/mark.c
@@ -1243,11 +1243,11 @@ void mark_adjust_buf(buf_T *buf, linenr_T line1, linenr_T line2, linenr_T amount
       if (win != curwin || by_api) {
         if (win->w_topline >= line1 && win->w_topline <= line2) {
           if (amount == MAXLNUM) {                  // topline is deleted
-            if (line1 <= 1) {
-              win->w_topline = 1;
+            if (by_api && amount_after > line1 - line2 - 1) {
+              // api: if the deleted region was replaced with new contents, topline will
+              // get adjusted later as an effect of the adjusted cursor in fix_cursor()
             } else {
-              // api: if the deleted region was replaced with new contents, display that
-              win->w_topline = (by_api && amount_after > line1 - line2 - 1) ? line1 : line1 - 1;
+              win->w_topline = MAX(line1 - 1, 1);
             }
           } else if (win->w_topline > line1) {
             // keep topline on the same line, unless inserting just
diff --git a/test/functional/api/buffer_spec.lua b/test/functional/api/buffer_spec.lua
index f46cf7a315..a560546d2d 100644
--- a/test/functional/api/buffer_spec.lua
+++ b/test/functional/api/buffer_spec.lua
@@ -150,16 +150,16 @@ describe('api/buf', function()
       ]],
       }
 
+      lines[5] = 'boogalo 5'
       api.nvim_buf_set_lines(buf, 0, -1, true, lines)
       screen:expect {
         grid = [[
         ^                    |
         {1:~                   }|*4
         {2:[No Name]           }|
-        line3               |
-        line4               |
-        line5               |
+        boogalo 5           |
         line6               |
+        {1:~                   }|*2
         {3:[No Name] [+]       }|
                             |
       ]],
@@ -171,10 +171,9 @@ describe('api/buf', function()
                             |
         {1:~                   }|*4
         {3:[No Name]           }|
-        line3               |
-        line4               |
-        line5               |
+        boogalo 5           |
         ^line6               |
+        {1:~                   }|*2
         {2:[No Name] [+]       }|
                             |
       ]],