diff -Naur qt-everywhere-src-5.12.4-orig/qtbase/src/network/kernel/qdnslookup.h qt-everywhere-src-5.12.4/qtbase/src/network/kernel/qdnslookup.h
--- qt-everywhere-src-5.12.4-orig/qtbase/src/network/kernel/qdnslookup.h	2019-06-12 23:59:14.000000000 +0300
+++ qt-everywhere-src-5.12.4/qtbase/src/network/kernel/qdnslookup.h	2019-06-15 15:26:47.147922800 +0300
@@ -206,6 +206,10 @@
     };
     Q_ENUM(Error)
 
+#ifdef PTR
+#define PTR_OLD_DEFINE PTR
+#undef PTR
+#endif
     enum Type
     {
         A = 1,
@@ -219,6 +223,10 @@
         TXT = 16
     };
     Q_ENUM(Type)
+// Set PTR back what it previously contained.
+#ifdef PTR_OLD_DEFINE
+#define PTR PTR_OLD_DEFINE
+#endif
 
     explicit QDnsLookup(QObject *parent = nullptr);
     QDnsLookup(Type type, const QString &name, QObject *parent = nullptr);