diff --git a/README.md b/README.md
index 04dc680..adc6dca 100644
--- a/README.md
+++ b/README.md
@@ -262,7 +262,7 @@ require("oil").setup({
     -- max_width and max_height can be integers or a float between 0 and 1 (e.g. 0.4 for 40%)
     max_width = 0,
     max_height = 0,
-    border = "rounded",
+    border = nil,
     win_options = {
       winblend = 0,
     },
@@ -307,7 +307,7 @@ require("oil").setup({
     min_height = { 5, 0.1 },
     -- optionally define an integer/float for the exact height of the preview window
     height = nil,
-    border = "rounded",
+    border = nil,
     win_options = {
       winblend = 0,
     },
@@ -320,7 +320,7 @@ require("oil").setup({
     max_height = { 10, 0.9 },
     min_height = { 5, 0.1 },
     height = nil,
-    border = "rounded",
+    border = nil,
     minimized_border = "none",
     win_options = {
       winblend = 0,
@@ -328,11 +328,11 @@ require("oil").setup({
   },
   -- Configuration for the floating SSH window
   ssh = {
-    border = "rounded",
+    border = nil,
   },
   -- Configuration for the floating keymaps help window
   keymaps_help = {
-    border = "rounded",
+    border = nil,
   },
 })
 ```
diff --git a/doc/oil.txt b/doc/oil.txt
index fdc7ca5..7086ffe 100644
--- a/doc/oil.txt
+++ b/doc/oil.txt
@@ -144,7 +144,7 @@ CONFIG                                                                *oil-confi
         -- max_width and max_height can be integers or a float between 0 and 1 (e.g. 0.4 for 40%)
         max_width = 0,
         max_height = 0,
-        border = "rounded",
+        border = nil,
         win_options = {
           winblend = 0,
         },
@@ -189,7 +189,7 @@ CONFIG                                                                *oil-confi
         min_height = { 5, 0.1 },
         -- optionally define an integer/float for the exact height of the preview window
         height = nil,
-        border = "rounded",
+        border = nil,
         win_options = {
           winblend = 0,
         },
@@ -202,7 +202,7 @@ CONFIG                                                                *oil-confi
         max_height = { 10, 0.9 },
         min_height = { 5, 0.1 },
         height = nil,
-        border = "rounded",
+        border = nil,
         minimized_border = "none",
         win_options = {
           winblend = 0,
@@ -210,11 +210,11 @@ CONFIG                                                                *oil-confi
       },
       -- Configuration for the floating SSH window
       ssh = {
-        border = "rounded",
+        border = nil,
       },
       -- Configuration for the floating keymaps help window
       keymaps_help = {
-        border = "rounded",
+        border = nil,
       },
     })
 <
diff --git a/lua/oil/config.lua b/lua/oil/config.lua
index 6797cc8..7b4e97c 100644
--- a/lua/oil/config.lua
+++ b/lua/oil/config.lua
@@ -127,7 +127,7 @@ local default_config = {
     -- max_width and max_height can be integers or a float between 0 and 1 (e.g. 0.4 for 40%)
     max_width = 0,
     max_height = 0,
-    border = "rounded",
+    border = nil,
     win_options = {
       winblend = 0,
     },
@@ -172,7 +172,7 @@ local default_config = {
     min_height = { 5, 0.1 },
     -- optionally define an integer/float for the exact height of the preview window
     height = nil,
-    border = "rounded",
+    border = nil,
     win_options = {
       winblend = 0,
     },
@@ -185,7 +185,7 @@ local default_config = {
     max_height = { 10, 0.9 },
     min_height = { 5, 0.1 },
     height = nil,
-    border = "rounded",
+    border = nil,
     minimized_border = "none",
     win_options = {
       winblend = 0,
@@ -193,11 +193,11 @@ local default_config = {
   },
   -- Configuration for the floating SSH window
   ssh = {
-    border = "rounded",
+    border = nil,
   },
   -- Configuration for the floating keymaps help window
   keymaps_help = {
-    border = "rounded",
+    border = nil,
   },
 }
 
@@ -412,6 +412,17 @@ M.setup = function(opts)
     end
   end
 
+  -- Backwards compatibility for old versions that don't support winborder
+  if vim.fn.has("nvim-0.11") == 0 then
+    new_conf = vim.tbl_deep_extend("keep", new_conf, {
+      float = { border = "rounded" },
+      confirmation = { border = "rounded" },
+      progress = { border = "rounded" },
+      ssh = { border = "rounded" },
+      keymaps_help = { border = "rounded" },
+    })
+  end
+
   -- Backwards compatibility. We renamed the 'preview' window config to be called 'confirmation'.
   if opts.preview and not opts.confirmation then
     new_conf.confirmation = vim.tbl_deep_extend("keep", opts.preview, default_config.confirmation)