diff --git a/clipboard_windows.go b/clipboard_windows.go
index 253bb93..0ea5568 100644
--- a/clipboard_windows.go
+++ b/clipboard_windows.go
@@ -7,6 +7,7 @@
 package clipboard
 
 import (
+	"errors"
 	"runtime"
 	"syscall"
 	"time"
@@ -33,6 +34,8 @@ var (
 	globalLock   = kernel32.NewProc("GlobalLock")
 	globalUnlock = kernel32.NewProc("GlobalUnlock")
 	lstrcpy      = kernel32.NewProc("lstrcpyW")
+
+	ErrFormatUnavailable = errors.New("clipboard format is unavailable")
 )
 
 // waitOpenClipboard opens the clipboard, waiting for up to a second to do so.
@@ -56,8 +59,8 @@ func readAll() (string, error) {
 	// Otherwise if the goroutine switch thread during execution (which is a common practice), the OpenClipboard and CloseClipboard will happen on two different threads, and it will result in a clipboard deadlock.
 	runtime.LockOSThread()
 	defer runtime.UnlockOSThread()
-	if formatAvailable, _, err := isClipboardFormatAvailable.Call(cfUnicodetext); formatAvailable == 0 {
-		return "", err
+	if formatAvailable, _, _ := isClipboardFormatAvailable.Call(cfUnicodetext); formatAvailable == 0 {
+		return "", ErrFormatUnavailable
 	}
 	err := waitOpenClipboard()
 	if err != nil {