diff --git a/doc/docgen.zig b/doc/docgen.zig
index 5332a62ac7..56d9a04412 100644
--- a/doc/docgen.zig
+++ b/doc/docgen.zig
@@ -55,7 +55,7 @@ pub fn main() !void {
         // TODO issue #709
         // disabled to pass CI tests, but obviously we want to implement this
         // and then remove this workaround
-        if (builtin.os == builtin.Os.linux) {
+        if (builtin.os != builtin.Os.windows) {
             os.deleteTree(allocator, tmp_dir_name) catch {};
         }
     }
diff --git a/std/os/index.zig b/std/os/index.zig
index d8e2fd7009..4b74af035e 100644
--- a/std/os/index.zig
+++ b/std/os/index.zig
@@ -1050,14 +1050,14 @@ const DeleteTreeError = error {
 };
 pub fn deleteTree(allocator: &Allocator, full_path: []const u8) DeleteTreeError!void {
     start_over: while (true) {
+        var got_access_denied = false;
         // First, try deleting the item as a file. This way we don't follow sym links.
         if (deleteFile(allocator, full_path)) {
             return;
         } else |err| switch (err) {
             error.FileNotFound => return,
-
-            error.AccessDenied,
             error.IsDir => {},
+            error.AccessDenied => got_access_denied = true,
 
             error.OutOfMemory,
             error.SymLinkLoop,
@@ -1072,7 +1072,12 @@ pub fn deleteTree(allocator: &Allocator, full_path: []const u8) DeleteTreeError!
         }
         {
             var dir = Dir.open(allocator, full_path) catch |err| switch (err) {
-                error.NotDir => continue :start_over,
+                error.NotDir => {
+                    if (got_access_denied) {
+                        return error.AccessDenied;
+                    }
+                    continue :start_over;
+                },
 
                 error.OutOfMemory,
                 error.AccessDenied,
diff --git a/std/os/test.zig b/std/os/test.zig
index 20d439cc48..9c718d5b6b 100644
--- a/std/os/test.zig
+++ b/std/os/test.zig
@@ -1,18 +1,25 @@
 const std = @import("../index.zig");
 const os = std.os;
-const debug = std.debug;
+const assert = std.debug.assert;
 const io = std.io;
 
 const a = std.debug.global_allocator;
 
+const builtin = @import("builtin");
+
 test "makePath, put some files in it, deleteTree" {
+    if (builtin.os == builtin.Os.windows) {
+        // TODO implement os.Dir for windows
+        // https://github.com/zig-lang/zig/issues/709
+        return;
+    }
     try os.makePath(a, "os_test_tmp/b/c");
     try io.writeFile(a, "os_test_tmp/b/c/file.txt", "nonsense");
     try io.writeFile(a, "os_test_tmp/b/file2.txt", "blah");
     try os.deleteTree(a, "os_test_tmp");
     if (os.Dir.open(a, "os_test_tmp")) |dir| {
-        debug.assert(false); // this should not happen!
+        @panic("expected error");
     } else |err| {
-        debug.assert(err == error.PathNotFound);
+        assert(err == error.PathNotFound);
     }
 }