diff --git a/Machines/Atari2600/Cartridges/Cartridge.hpp b/Machines/Atari2600/Cartridges/Cartridge.hpp
index 8d49f9f58..20f52c9a9 100644
--- a/Machines/Atari2600/Cartridges/Cartridge.hpp
+++ b/Machines/Atari2600/Cartridges/Cartridge.hpp
@@ -188,7 +188,7 @@ template<class T> class Cartridge:
 		std::vector<uint8_t> rom_;
 
 	private:
-		BusExtender bus_extender_;
+		T bus_extender_;
 };
 
 }
diff --git a/Machines/Atari2600/Cartridges/CommaVid.hpp b/Machines/Atari2600/Cartridges/CommaVid.hpp
index 9a389b43f..79bee917b 100644
--- a/Machines/Atari2600/Cartridges/CommaVid.hpp
+++ b/Machines/Atari2600/Cartridges/CommaVid.hpp
@@ -9,11 +9,15 @@
 #ifndef Atari2600_CartridgeCommaVid_hpp
 #define Atari2600_CartridgeCommaVid_hpp
 
+#include "Cartridge.hpp"
+
 namespace Atari2600 {
 namespace Cartridge {
 
 class CommaVid: public BusExtender {
 	public:
+		CommaVid(uint8_t *rom_base, size_t rom_size) : BusExtender(rom_base, rom_size) {}
+
 		void perform_bus_operation(CPU::MOS6502::BusOperation operation, uint16_t address, uint8_t *value) {
 			if(!(address & 0x1000)) return;
 			address &= 0x1fff;