diff --git a/v1/errors_windows.go b/v1/errors_windows.go
index cb581c9..a726d91 100644
--- a/v1/errors_windows.go
+++ b/v1/errors_windows.go
@@ -9,9 +9,8 @@ import (
 // isConnCloseError returns true if the error is from the peer closing the
 // connection early.
 func isConnCloseError(err error) bool {
-	const WSAEPROTOTYPE = syscall.Errno(10041)
 	return errors.Is(err, io.EOF) ||
-		errors.Is(err, WSAEPROTOTYPE) ||
+		errors.Is(err, syscall.Errno(10041)) || // WSAEPROTOTYPE
 		errors.Is(err, syscall.WSAECONNABORTED) ||
 		errors.Is(err, syscall.WSAECONNRESET)
 }
diff --git a/v2/errors_windows.go b/v2/errors_windows.go
index cb581c9..a726d91 100644
--- a/v2/errors_windows.go
+++ b/v2/errors_windows.go
@@ -9,9 +9,8 @@ import (
 // isConnCloseError returns true if the error is from the peer closing the
 // connection early.
 func isConnCloseError(err error) bool {
-	const WSAEPROTOTYPE = syscall.Errno(10041)
 	return errors.Is(err, io.EOF) ||
-		errors.Is(err, WSAEPROTOTYPE) ||
+		errors.Is(err, syscall.Errno(10041)) || // WSAEPROTOTYPE
 		errors.Is(err, syscall.WSAECONNABORTED) ||
 		errors.Is(err, syscall.WSAECONNRESET)
 }