diff --git a/lib/kpty.h b/lib/kpty.h
index 24457a5..ab34f6e 100644
--- a/lib/kpty.h
+++ b/lib/kpty.h
@@ -25,7 +25,7 @@
 
 #include <QObject>
 
-struct KPtyPrivate;
+class KPtyPrivate;
 struct termios;
 
 /**
diff --git a/lib/kpty_p.h b/lib/kpty_p.h
index 3f6bb88..4f865b8 100644
--- a/lib/kpty_p.h
+++ b/lib/kpty_p.h
@@ -27,7 +27,8 @@
 
 #include <QByteArray>
 
-struct KPtyPrivate {
+class KPtyPrivate {
+public:
 
     Q_DECLARE_PUBLIC(KPty)
 
diff --git a/lib/kptydevice.h b/lib/kptydevice.h
index 3ef8d17..0fccd62 100644
--- a/lib/kptydevice.h
+++ b/lib/kptydevice.h
@@ -41,7 +41,7 @@ class QSocketNotifier;
 #define Q_DECLARE_PRIVATE_MI(Class, SuperClass) \
     inline Class##Private* d_func() { return reinterpret_cast<Class##Private *>(SuperClass::d_ptr); } \
     inline const Class##Private* d_func() const { return reinterpret_cast<const Class##Private *>(SuperClass::d_ptr); } \
-    friend class Class##Private;
+    friend struct Class##Private;
 
 /**
  * Encapsulates KPty into a QIODevice, so it can be used with Q*Stream, etc.
diff --git a/lib/kptyprocess.h b/lib/kptyprocess.h
index 15e4de4..1270c47 100644
--- a/lib/kptyprocess.h
+++ b/lib/kptyprocess.h
@@ -37,7 +37,7 @@
 
 class KPtyDevice;
 
-struct KPtyProcessPrivate;
+class KPtyProcessPrivate;
 
 /**
  * This class extends KProcess by support for PTYs (pseudo TTYs).
@@ -155,7 +155,8 @@ private:
 // private data //
 //////////////////
 
-struct KPtyProcessPrivate : KProcessPrivate {
+class KPtyProcessPrivate : public KProcessPrivate {
+public:
     KPtyProcessPrivate() :
         ptyChannels(KPtyProcess::NoChannels),
         addUtmp(false)