bool wxFileInputStream::IsOk() const
 {
-    return wxStreamBase::IsOk() && m_file->IsOpened();
+    return wxInputStream::IsOk() && m_file->IsOpened();
 }
 
 // ----------------------------------------------------------------------------
 
 bool wxFileOutputStream::IsOk() const
 {
-    return wxStreamBase::IsOk() && m_file->IsOpened();
+    return wxOutputStream::IsOk() && m_file->IsOpened();
 }
 
 // ----------------------------------------------------------------------------
 
 bool wxFileStream::IsOk() const
 {
-    return wxFileOutputStream::IsOk() && wxFileInputStream::m_file->IsOpened();
+    return wxFileOutputStream::IsOk() && wxFileInputStream::IsOk();
 }
 
-#endif //wxUSE_FILE
+#endif // wxUSE_FILE
 
 #if wxUSE_FFILE
 
     wxFFileOutputStream::m_file = wxFFileInputStream::m_file;
 }
 
+bool wxFFileStream::IsOk() const
+{
+    return wxFFileOutputStream::IsOk() && wxFFileInputStream::IsOk();
+}
+
 #endif //wxUSE_FFILE
 
 #endif // wxUSE_STREAMS