diff --git a/Source/Core/Common/BitSet.h b/Source/Core/Common/BitSet.h
index f8506e7c89..4425b6067c 100644
--- a/Source/Core/Common/BitSet.h
+++ b/Source/Core/Common/BitSet.h
@@ -5,14 +5,14 @@
 #include <cstddef>
 #include <initializer_list>
 #include <type_traits>
-#include "CommonTypes.h"
-
-// Helper functions:
+#include "Common/CommonTypes.h"
 
 #ifdef _WIN32
 
 #include <intrin.h>
 
+namespace Common
+{
 template <typename T>
 constexpr int CountSetBits(T v)
 {
@@ -49,6 +49,8 @@ inline int LeastSignificantSetBit(u64 val)
   return (int)index;
 }
 #else
+namespace Common
+{
 constexpr int CountSetBits(u8 val)
 {
   return __builtin_popcount(val);
@@ -83,9 +85,6 @@ inline int LeastSignificantSetBit(u64 val)
 }
 #endif
 
-// namespace avoids conflict with OS X Carbon; don't use BitSet<T> directly
-namespace BS
-{
 // Similar to std::bitset, this is a class which encapsulates a bitset, i.e.
 // using the set bits of an integer to represent a set of integers.  Like that
 // class, it acts like an array of bools:
@@ -207,9 +206,9 @@ public:
   constexpr Iterator end() const { return Iterator(m_val, -1); }
   IntTy m_val;
 };
-}
+}  // namespace Common
 
-typedef BS::BitSet<u8> BitSet8;
-typedef BS::BitSet<u16> BitSet16;
-typedef BS::BitSet<u32> BitSet32;
-typedef BS::BitSet<u64> BitSet64;
+using BitSet8 = Common::BitSet<u8>;
+using BitSet16 = Common::BitSet<u16>;
+using BitSet32 = Common::BitSet<u32>;
+using BitSet64 = Common::BitSet<u64>;
diff --git a/Source/Core/VideoBackends/D3D/D3DState.cpp b/Source/Core/VideoBackends/D3D/D3DState.cpp
index 8a2862479b..25742d2a65 100644
--- a/Source/Core/VideoBackends/D3D/D3DState.cpp
+++ b/Source/Core/VideoBackends/D3D/D3DState.cpp
@@ -28,8 +28,8 @@ void StateManager::Apply()
   if (!m_dirtyFlags)
     return;
 
-  int textureMaskShift = LeastSignificantSetBit((u32)DirtyFlag_Texture0);
-  int samplerMaskShift = LeastSignificantSetBit((u32)DirtyFlag_Sampler0);
+  const int textureMaskShift = Common::LeastSignificantSetBit((u32)DirtyFlag_Texture0);
+  const int samplerMaskShift = Common::LeastSignificantSetBit((u32)DirtyFlag_Sampler0);
 
   u32 dirtyTextures =
       (m_dirtyFlags &
@@ -105,7 +105,7 @@ void StateManager::Apply()
 
   while (dirtyTextures)
   {
-    int index = LeastSignificantSetBit(dirtyTextures);
+    const int index = Common::LeastSignificantSetBit(dirtyTextures);
     if (m_current.textures[index] != m_pending.textures[index])
     {
       D3D::context->PSSetShaderResources(index, 1, &m_pending.textures[index]);
@@ -117,7 +117,7 @@ void StateManager::Apply()
 
   while (dirtySamplers)
   {
-    int index = LeastSignificantSetBit(dirtySamplers);
+    const int index = Common::LeastSignificantSetBit(dirtySamplers);
     if (m_current.samplers[index] != m_pending.samplers[index])
     {
       D3D::context->PSSetSamplers(index, 1, &m_pending.samplers[index]);
@@ -187,7 +187,7 @@ void StateManager::SetTextureByMask(u32 textureSlotMask, ID3D11ShaderResourceVie
 {
   while (textureSlotMask)
   {
-    int index = LeastSignificantSetBit(textureSlotMask);
+    const int index = Common::LeastSignificantSetBit(textureSlotMask);
     SetTexture(index, srv);
     textureSlotMask &= ~(1 << index);
   }