diff --git a/Source/Core/Core/HW/EXI/EXI_Device.cpp b/Source/Core/Core/HW/EXI/EXI_Device.cpp
index 06df862990..05d0a4818f 100644
--- a/Source/Core/Core/HW/EXI/EXI_Device.cpp
+++ b/Source/Core/Core/HW/EXI/EXI_Device.cpp
@@ -40,6 +40,10 @@ u32 IEXIDevice::ImmRead(u32 size)
   return result;
 }
 
+void IEXIDevice::ImmReadWrite(u32& data, u32 size)
+{
+}
+
 void IEXIDevice::DMAWrite(u32 address, u32 size)
 {
   while (size--)
@@ -59,6 +63,42 @@ void IEXIDevice::DMARead(u32 address, u32 size)
   }
 }
 
+IEXIDevice* IEXIDevice::FindDevice(TEXIDevices device_type, int custom_index)
+{
+  return (device_type == m_device_type) ? this : nullptr;
+}
+
+bool IEXIDevice::UseDelayedTransferCompletion() const
+{
+  return false;
+}
+
+bool IEXIDevice::IsPresent() const
+{
+  return false;
+}
+
+void IEXIDevice::SetCS(int cs)
+{
+}
+
+void IEXIDevice::DoState(PointerWrap& p)
+{
+}
+
+void IEXIDevice::PauseAndLock(bool do_lock, bool resume_on_unlock)
+{
+}
+
+bool IEXIDevice::IsInterruptSet()
+{
+  return false;
+}
+
+void IEXIDevice::TransferByte(u8& byte)
+{
+}
+
 // F A C T O R Y
 std::unique_ptr<IEXIDevice> EXIDevice_Create(TEXIDevices device_type, const int channel_num)
 {
diff --git a/Source/Core/Core/HW/EXI/EXI_Device.h b/Source/Core/Core/HW/EXI/EXI_Device.h
index 3b83cecb09..c660d4098b 100644
--- a/Source/Core/Core/HW/EXI/EXI_Device.h
+++ b/Source/Core/Core/HW/EXI/EXI_Device.h
@@ -36,31 +36,31 @@ public:
   // Immediate copy functions
   virtual void ImmWrite(u32 data, u32 size);
   virtual u32 ImmRead(u32 size);
-  virtual void ImmReadWrite(u32& /*data*/, u32 /*size*/) {}
+  virtual void ImmReadWrite(u32& data, u32 size);
+
   // DMA copy functions
   virtual void DMAWrite(u32 address, u32 size);
   virtual void DMARead(u32 address, u32 size);
 
-  virtual bool UseDelayedTransferCompletion() const { return false; }
-  virtual bool IsPresent() const { return false; }
-  virtual void SetCS(int) {}
-  virtual void DoState(PointerWrap&) {}
-  virtual void PauseAndLock(bool do_lock, bool resume_on_unlock = true) {}
-  virtual IEXIDevice* FindDevice(TEXIDevices device_type, int custom_index = -1)
-  {
-    return (device_type == m_device_type) ? this : nullptr;
-  }
+  virtual IEXIDevice* FindDevice(TEXIDevices device_type, int custom_index = -1);
+
+  virtual bool UseDelayedTransferCompletion() const;
+  virtual bool IsPresent() const;
+  virtual void SetCS(int cs);
+  virtual void DoState(PointerWrap& p);
+  virtual void PauseAndLock(bool do_lock, bool resume_on_unlock = true);
 
   // Is generating interrupt ?
-  virtual bool IsInterruptSet() { return false; }
-  // for savestates. storing it here seemed cleaner than requiring each implementation to report its
-  // type.
-  // I know this class is set up like an interface, but no code requires it to be strictly such.
+  virtual bool IsInterruptSet();
+
+  // For savestates. storing it here seemed cleaner than requiring each implementation to report its
+  // type. I know this class is set up like an interface, but no code requires it to be strictly
+  // such.
   TEXIDevices m_device_type;
 
 private:
   // Byte transfer function for this device
-  virtual void TransferByte(u8&) {}
+  virtual void TransferByte(u8& byte);
 };
 
 std::unique_ptr<IEXIDevice> EXIDevice_Create(const TEXIDevices device_type, const int channel_num);