diff --git a/solver/socketprovider_windows.go b/solver/socketprovider_windows.go
index b8439e69..aa47b625 100644
--- a/solver/socketprovider_windows.go
+++ b/solver/socketprovider_windows.go
@@ -13,7 +13,7 @@ import (
 )
 
 func dialStream(id string) (net.Conn, error) {
-	if !strings.HasPrefix(id, unixPrefix) {
+	if !strings.HasPrefix(id, npipePrefix) {
 		return nil, fmt.Errorf("invalid socket forward key %s", id)
 	}