diff --git a/Source/Core/Core/HW/WiimoteEmu/Attachment/Nunchuk.cpp b/Source/Core/Core/HW/WiimoteEmu/Attachment/Nunchuk.cpp
index 6bd4bd6c1f..4cced8be4d 100644
--- a/Source/Core/Core/HW/WiimoteEmu/Attachment/Nunchuk.cpp
+++ b/Source/Core/Core/HW/WiimoteEmu/Attachment/Nunchuk.cpp
@@ -69,6 +69,35 @@ Nunchuk::Nunchuk(ExtensionReg& reg) : Attachment(_trans("Nunchuk"), reg)
   m_shake_hard->controls.emplace_back(new ControllerEmu::Input(ControllerEmu::DoNotTranslate, "Z"));
 
   m_id = nunchuk_id;
+
+  // Build calibration data:
+  m_calibration = {{
+      // Accel Zero X,Y,Z:
+      ACCEL_ZERO_G,
+      ACCEL_ZERO_G,
+      ACCEL_ZERO_G,
+      // Possibly LSBs of zero values:
+      0x00,
+      // Accel 1G X,Y,Z:
+      ACCEL_ONE_G,
+      ACCEL_ONE_G,
+      ACCEL_ONE_G,
+      // Possibly LSBs of 1G values:
+      0x00,
+      // Stick X max,min,center:
+      STICK_CENTER + STICK_RADIUS,
+      STICK_CENTER - STICK_RADIUS,
+      STICK_CENTER,
+      // Stick Y max,min,center:
+      STICK_CENTER + STICK_RADIUS,
+      STICK_CENTER - STICK_RADIUS,
+      STICK_CENTER,
+      // 2 checksum bytes calculated below:
+      0x00,
+      0x00,
+  }};
+
+  UpdateCalibrationDataChecksum(m_calibration);
 }
 
 void Nunchuk::GetState(u8* const data)
@@ -186,4 +215,4 @@ void Nunchuk::LoadDefaults(const ControllerInterface& ciface)
   m_buttons->SetControlExpression(1, "Shift_L");    // Z
 #endif
 }
-}
+}  // namespace WiimoteEmu
diff --git a/Source/Core/Core/HW/WiimoteEmu/WiimoteEmu.cpp b/Source/Core/Core/HW/WiimoteEmu/WiimoteEmu.cpp
index adff30830c..7e33d2492d 100644
--- a/Source/Core/Core/HW/WiimoteEmu/WiimoteEmu.cpp
+++ b/Source/Core/Core/HW/WiimoteEmu/WiimoteEmu.cpp
@@ -11,6 +11,7 @@
 #include <cstddef>
 #include <cstring>
 #include <mutex>
+#include <numeric>
 
 #include "Common/ChunkFile.h"
 #include "Common/CommonTypes.h"
@@ -101,6 +102,15 @@ static const ReportFeatures reporting_mode_features[] = {
     {0, 0, 0, 0, 23},
 };
 
+// Used for extension calibration data:
+// Last two bytes are the sum of the previous bytes plus 0x55 and 0xaa
+void UpdateCalibrationDataChecksum(std::array<u8, 0x10>& data)
+{
+  const u8 ck1 = std::accumulate(std::begin(data), std::end(data) - 2, (u8)0x55);
+  data[0xe] = ck1;
+  data[0xf] = ck1 + 0x55;
+}
+
 void EmulateShake(AccelData* const accel, ControllerEmu::Buttons* const buttons_group,
                   const double intensity, u8* const shake_step)
 {
@@ -1028,8 +1038,8 @@ void Wiimote::LoadDefaults(const ControllerInterface& ciface)
   m_buttons->SetControlExpression(0, "Click 1");  // A
   m_buttons->SetControlExpression(1, "Click 3");  // B
 #else
-  m_buttons->SetControlExpression(0, "Click 0");  // A
-  m_buttons->SetControlExpression(1, "Click 1");  // B
+  m_buttons->SetControlExpression(0, "Click 0");            // A
+  m_buttons->SetControlExpression(1, "Click 1");            // B
 #endif
   m_buttons->SetControlExpression(2, "1");  // 1
   m_buttons->SetControlExpression(3, "2");  // 2
diff --git a/Source/Core/Core/HW/WiimoteEmu/WiimoteEmu.h b/Source/Core/Core/HW/WiimoteEmu/WiimoteEmu.h
index 4a1bca6d9a..6b50dc1296 100644
--- a/Source/Core/Core/HW/WiimoteEmu/WiimoteEmu.h
+++ b/Source/Core/Core/HW/WiimoteEmu/WiimoteEmu.h
@@ -34,7 +34,7 @@ class ModifySettingsButton;
 class NumericSetting;
 class Output;
 class Tilt;
-}
+}  // namespace ControllerEmu
 
 namespace WiimoteReal
 {
@@ -181,6 +181,8 @@ struct ExtensionReg
 };
 #pragma pack(pop)
 
+void UpdateCalibrationDataChecksum(std::array<u8, 0x10>& data);
+
 void EmulateShake(AccelData* accel, ControllerEmu::Buttons* buttons_group, double intensity,
                   u8* shake_step);
 
@@ -377,4 +379,4 @@ private:
 
 #pragma pack(pop)
 };
-}
+}  // namespace WiimoteEmu