diff --git a/libs/main/io_devices/piconfig.h b/libs/main/io_devices/piconfig.h
index 82e213b8..ea9ae396 100644
--- a/libs/main/io_devices/piconfig.h
+++ b/libs/main/io_devices/piconfig.h
@@ -63,6 +63,8 @@ class PIP_EXPORT PIConfig {
 	friend class Branch;
 
 public:
+	NO_COPY_CLASS(PIConfig);
+
 	//! Contructs and read configuration file at path "path" in mode "mode"
 	PIConfig(const PIString & path, PIIODevice::DeviceMode mode = PIIODevice::ReadWrite);
 
diff --git a/libs/main/io_devices/piiostream.h b/libs/main/io_devices/piiostream.h
index cfe4e162..bd969f8c 100644
--- a/libs/main/io_devices/piiostream.h
+++ b/libs/main/io_devices/piiostream.h
@@ -62,7 +62,7 @@ public:
 	}
 
 private:
-	PIIODevice * dev;
+	PIIODevice * dev = nullptr;
 };
 
 
diff --git a/libs/main/io_devices/piiostring.h b/libs/main/io_devices/piiostring.h
index 419cea45..b24033b9 100644
--- a/libs/main/io_devices/piiostring.h
+++ b/libs/main/io_devices/piiostring.h
@@ -110,8 +110,8 @@ protected:
 	ssize_t writeDevice(const void * data, ssize_t max_size) override;
 	DeviceInfoFlags deviceInfoFlags() const override { return PIIODevice::Sequential | PIIODevice::Reliable; }
 
-	ssize_t pos;
-	PIString * str;
+	ssize_t pos    = 0;
+	PIString * str = nullptr;
 };
 
 #endif // PIIOSTRING_H