diff --git a/backend/local/local.go b/backend/local/local.go
index af170e585..8d2fb7b81 100644
--- a/backend/local/local.go
+++ b/backend/local/local.go
@@ -10,7 +10,6 @@ import (
 	"os"
 	"path"
 	"path/filepath"
-	"regexp"
 	"runtime"
 	"strings"
 	"sync"
@@ -1226,7 +1225,7 @@ func cleanRootPath(s string, noUNC bool, enc encoder.MultiEncoder) string {
 
 		if !noUNC {
 			// Convert to UNC
-			s = uncPath(s)
+			s = file.UNCPath(s)
 		}
 		return s
 	}
@@ -1240,28 +1239,6 @@ func cleanRootPath(s string, noUNC bool, enc encoder.MultiEncoder) string {
 	return s
 }
 
-// Pattern to match a windows absolute path: "c:\" and similar
-var isAbsWinDrive = regexp.MustCompile(`^[a-zA-Z]\:\\`)
-
-// uncPath converts an absolute Windows path
-// to a UNC long path.
-func uncPath(l string) string {
-	// If prefix is "\\", we already have a UNC path or server.
-	if strings.HasPrefix(l, `\\`) {
-		// If already long path, just keep it
-		if strings.HasPrefix(l, `\\?\`) {
-			return l
-		}
-
-		// Trim "\\" from path and add UNC prefix.
-		return `\\?\UNC\` + strings.TrimPrefix(l, `\\`)
-	}
-	if isAbsWinDrive.MatchString(l) {
-		return `\\?\` + l
-	}
-	return l
-}
-
 // Check the interfaces are satisfied
 var (
 	_ fs.Fs             = &Fs{}
diff --git a/backend/local/tests_test.go b/backend/local/tests_test.go
index 284a63067..e67c72705 100644
--- a/backend/local/tests_test.go
+++ b/backend/local/tests_test.go
@@ -5,49 +5,6 @@ import (
 	"testing"
 )
 
-var uncTestPaths = []string{
-	`C:\Ba*d\P|a?t<h>\Windows\Folder`,
-	`C:\Windows\Folder`,
-	`\\?\C:\Windows\Folder`,
-	`\\?\UNC\server\share\Desktop`,
-	`\\?\unC\server\share\Desktop\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path`,
-	`\\server\share\Desktop\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path`,
-	`C:\Desktop\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path`,
-	`C:\AbsoluteToRoot\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path`,
-	`\\server\share\Desktop`,
-	`\\?\UNC\\share\folder\Desktop`,
-	`\\server\share`,
-}
-
-var uncTestPathsResults = []string{
-	`\\?\C:\Ba*d\P|a?t<h>\Windows\Folder`,
-	`\\?\C:\Windows\Folder`,
-	`\\?\C:\Windows\Folder`,
-	`\\?\UNC\server\share\Desktop`,
-	`\\?\unC\server\share\Desktop\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path`,
-	`\\?\UNC\server\share\Desktop\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path`,
-	`\\?\C:\Desktop\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path`,
-	`\\?\C:\AbsoluteToRoot\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path`,
-	`\\?\UNC\server\share\Desktop`,
-	`\\?\UNC\\share\folder\Desktop`,
-	`\\?\UNC\server\share`,
-}
-
-// Test that UNC paths are converted.
-func TestUncPaths(t *testing.T) {
-	for i, p := range uncTestPaths {
-		unc := uncPath(p)
-		if unc != uncTestPathsResults[i] {
-			t.Fatalf("UNC test path\nInput:%s\nOutput:%s\nExpected:%s", p, unc, uncTestPathsResults[i])
-		}
-		// Test we don't add more.
-		unc = uncPath(unc)
-		if unc != uncTestPathsResults[i] {
-			t.Fatalf("UNC test path\nInput:%s\nOutput:%s\nExpected:%s", p, unc, uncTestPathsResults[i])
-		}
-	}
-}
-
 // Test Windows character replacements
 var testsWindows = [][2]string{
 	{`c:\temp`, `c:\temp`},
diff --git a/lib/file/unc.go b/lib/file/unc.go
new file mode 100644
index 000000000..41661336d
--- /dev/null
+++ b/lib/file/unc.go
@@ -0,0 +1,10 @@
+//+build !windows
+
+package file
+
+// UNCPath converts an absolute Windows path to a UNC long path.
+//
+// It does nothing on non windows platforms
+func UNCPath(l string) string {
+	return l
+}
diff --git a/lib/file/unc_test.go b/lib/file/unc_test.go
new file mode 100644
index 000000000..5a22fe8ca
--- /dev/null
+++ b/lib/file/unc_test.go
@@ -0,0 +1,48 @@
+//+build windows
+
+package file
+
+import "testing"
+
+var uncTestPaths = []string{
+	`C:\Ba*d\P|a?t<h>\Windows\Folder`,
+	`C:\Windows\Folder`,
+	`\\?\C:\Windows\Folder`,
+	`\\?\UNC\server\share\Desktop`,
+	`\\?\unC\server\share\Desktop\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path`,
+	`\\server\share\Desktop\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path`,
+	`C:\Desktop\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path`,
+	`C:\AbsoluteToRoot\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path`,
+	`\\server\share\Desktop`,
+	`\\?\UNC\\share\folder\Desktop`,
+	`\\server\share`,
+}
+
+var uncTestPathsResults = []string{
+	`\\?\C:\Ba*d\P|a?t<h>\Windows\Folder`,
+	`\\?\C:\Windows\Folder`,
+	`\\?\C:\Windows\Folder`,
+	`\\?\UNC\server\share\Desktop`,
+	`\\?\unC\server\share\Desktop\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path`,
+	`\\?\UNC\server\share\Desktop\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path`,
+	`\\?\C:\Desktop\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path`,
+	`\\?\C:\AbsoluteToRoot\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path\Very Long path`,
+	`\\?\UNC\server\share\Desktop`,
+	`\\?\UNC\\share\folder\Desktop`,
+	`\\?\UNC\server\share`,
+}
+
+// Test that UNC paths are converted.
+func TestUncPaths(t *testing.T) {
+	for i, p := range uncTestPaths {
+		unc := UNCPath(p)
+		if unc != uncTestPathsResults[i] {
+			t.Fatalf("UNC test path\nInput:%s\nOutput:%s\nExpected:%s", p, unc, uncTestPathsResults[i])
+		}
+		// Test we don't add more.
+		unc = UNCPath(unc)
+		if unc != uncTestPathsResults[i] {
+			t.Fatalf("UNC test path\nInput:%s\nOutput:%s\nExpected:%s", p, unc, uncTestPathsResults[i])
+		}
+	}
+}
diff --git a/lib/file/unc_windows.go b/lib/file/unc_windows.go
new file mode 100644
index 000000000..5881befed
--- /dev/null
+++ b/lib/file/unc_windows.go
@@ -0,0 +1,31 @@
+//+build windows
+
+package file
+
+import (
+	"regexp"
+	"strings"
+)
+
+// Pattern to match a windows absolute path: "c:\" and similar
+var isAbsWinDrive = regexp.MustCompile(`^[a-zA-Z]\:\\`)
+
+// UNCPath converts an absolute Windows path to a UNC long path.
+//
+// It does nothing on non windows platforms
+func UNCPath(l string) string {
+	// If prefix is "\\", we already have a UNC path or server.
+	if strings.HasPrefix(l, `\\`) {
+		// If already long path, just keep it
+		if strings.HasPrefix(l, `\\?\`) {
+			return l
+		}
+
+		// Trim "\\" from path and add UNC prefix.
+		return `\\?\UNC\` + strings.TrimPrefix(l, `\\`)
+	}
+	if isAbsWinDrive.MatchString(l) {
+		return `\\?\` + l
+	}
+	return l
+}