diff --git a/Source/Core/InputCommon/ControllerInterface/CoreDevice.cpp b/Source/Core/InputCommon/ControllerInterface/CoreDevice.cpp
index cfced12e80..377ea4444f 100644
--- a/Source/Core/InputCommon/ControllerInterface/CoreDevice.cpp
+++ b/Source/Core/InputCommon/ControllerInterface/CoreDevice.cpp
@@ -130,39 +130,43 @@ bool Device::Control::IsHidden() const
   return false;
 }
 
-ControlState Device::FullAnalogSurface::GetState() const
+class FullAnalogSurface final : public Device::Input
 {
-  return (1 + std::max(0.0, m_high.GetState()) - std::max(0.0, m_low.GetState())) / 2;
-}
+public:
+  FullAnalogSurface(Input* low, Input* high) : m_low(*low), m_high(*high) {}
 
-std::string Device::FullAnalogSurface::GetName() const
-{
-  // E.g. "Full Axis X+"
-  return "Full " + m_high.GetName();
-}
+  ControlState GetState() const override
+  {
+    return (1 + std::max(0.0, m_high.GetState()) - std::max(0.0, m_low.GetState())) / 2;
+  }
 
-bool Device::FullAnalogSurface::IsDetectable() const
-{
-  return m_low.IsDetectable() && m_high.IsDetectable();
-}
+  std::string GetName() const override
+  {
+    // E.g. "Full Axis X+"
+    return "Full " + m_high.GetName();
+  }
 
-bool Device::FullAnalogSurface::IsHidden() const
-{
-  return m_low.IsHidden() && m_high.IsHidden();
-}
+  bool IsDetectable() const override { return m_low.IsDetectable() && m_high.IsDetectable(); }
 
-bool Device::FullAnalogSurface::IsMatchingName(std::string_view name) const
-{
-  if (Control::IsMatchingName(name))
-    return true;
+  bool IsHidden() const override { return m_low.IsHidden() && m_high.IsHidden(); }
 
-  // Old naming scheme was "Axis X-+" which is too visually similar to "Axis X+".
-  // This has caused countless problems for users with mysterious misconfigurations.
-  // We match this old name to support old configurations.
-  const auto old_name = m_low.GetName() + *m_high.GetName().rbegin();
+  bool IsMatchingName(std::string_view name) const override
+  {
+    if (Control::IsMatchingName(name))
+      return true;
 
-  return old_name == name;
-}
+    // Old naming scheme was "Axis X-+" which is too visually similar to "Axis X+".
+    // This has caused countless problems for users with mysterious misconfigurations.
+    // We match this old name to support old configurations.
+    const auto old_name = m_low.GetName() + *m_high.GetName().rbegin();
+
+    return old_name == name;
+  }
+
+private:
+  Input& m_low;
+  Input& m_high;
+};
 
 void Device::AddFullAnalogSurfaceInputs(Input* low, Input* high)
 {
diff --git a/Source/Core/InputCommon/ControllerInterface/CoreDevice.h b/Source/Core/InputCommon/ControllerInterface/CoreDevice.h
index b34e6a9d15..cd8256396e 100644
--- a/Source/Core/InputCommon/ControllerInterface/CoreDevice.h
+++ b/Source/Core/InputCommon/ControllerInterface/CoreDevice.h
@@ -163,21 +163,6 @@ protected:
   void AddInput(Input* const i);
   void AddOutput(Output* const o);
 
-  class FullAnalogSurface final : public Input
-  {
-  public:
-    FullAnalogSurface(Input* low, Input* high) : m_low(*low), m_high(*high) {}
-    ControlState GetState() const override;
-    std::string GetName() const override;
-    bool IsDetectable() const override;
-    bool IsHidden() const override;
-    bool IsMatchingName(std::string_view name) const override;
-
-  private:
-    Input& m_low;
-    Input& m_high;
-  };
-
   // Pass Inputs for center-neutral (- and +) directions of some axis.
   // This function adds those Inputs and also a FullAnalogSurface Input for each direction.
   // This is only needed when it's not known if the particular axis is neutral in the center