diff --git a/lib/file/mkdir_windows.go b/lib/file/mkdir_windows.go
index 73a82ac62..929587fd8 100644
--- a/lib/file/mkdir_windows.go
+++ b/lib/file/mkdir_windows.go
@@ -53,7 +53,7 @@ func MkdirAll(path string, perm os.FileMode) error {
 				j--
 			}
 			if j > 1 {
-				if path[:j-1] != `\\?\UNC` {
+				if path[:j-1] != `\\?\UNC` && path[:j-1] != `\\?` {
 					// Create parent.
 					err = MkdirAll(path[:j-1], perm)
 					if err != nil {
diff --git a/lib/file/mkdir_windows_test.go b/lib/file/mkdir_windows_test.go
index 2750e2dc3..a969f2d7f 100644
--- a/lib/file/mkdir_windows_test.go
+++ b/lib/file/mkdir_windows_test.go
@@ -89,7 +89,7 @@ func checkMkdirAll(t *testing.T, path string, valid bool, errormsgs ...string) {
 				ok = true
 			}
 		}
-		assert.True(t, ok, err.Error())
+		assert.True(t, ok, fmt.Sprintf("Error message '%v' didn't match any of %v", err, errormsgs))
 	}
 }
 
@@ -114,7 +114,7 @@ func TestMkdirAllOnDrive(t *testing.T) {
 
 	checkMkdirAll(t, drive, true, "")
 	checkMkdirAll(t, drive+`\`, true, "")
-	checkMkdirAll(t, `\\?\`+drive, true, "")
+	// checkMkdirAll(t, `\\?\`+drive, true, "") - this isn't actually a Valid Windows path - this test used to work under go1.21.3 but fails under go1.21.4
 	checkMkdirAll(t, `\\?\`+drive+`\`, true, "")
 	checkMkdirAllSubdirs(t, path, true, "")
 	checkMkdirAllSubdirs(t, `\\?\`+path, true, "")
@@ -129,10 +129,11 @@ func TestMkdirAllOnDrive(t *testing.T) {
 // "mkdir \\?\A:\: The system cannot find the path specified."
 func TestMkdirAllOnUnusedDrive(t *testing.T) {
 	path := unusedDrive(t)
-	errormsg := fmt.Sprintf("mkdir %s\\: The system cannot find the path specified.", path)
+	errormsg := fmt.Sprintf(`mkdir %s\: The system cannot find the path specified.`, path)
 	checkMkdirAllSubdirs(t, path, false, errormsg)
-	errormsg = fmt.Sprintf("mkdir \\\\?\\%s\\: The system cannot find the path specified.", path)
-	checkMkdirAllSubdirs(t, `\\?\`+path, false, errormsg)
+	errormsg1 := fmt.Sprintf(`mkdir \\?\%s\: The system cannot find the path specified.`, path) // pre go1.21.4
+	errormsg2 := fmt.Sprintf(`mkdir \\?\%s: The system cannot find the file specified.`, path)  // go1.21.4 and after
+	checkMkdirAllSubdirs(t, `\\?\`+path, false, errormsg1, errormsg2)
 }
 
 // Testing paths on unknown network host