diff --git a/lib/hkStubs/Havok/Common/Base/Math/Quaternion/hkQuaternionf.h b/lib/hkStubs/Havok/Common/Base/Math/Quaternion/hkQuaternionf.h
index f404ba78..947a5558 100644
--- a/lib/hkStubs/Havok/Common/Base/Math/Quaternion/hkQuaternionf.h
+++ b/lib/hkStubs/Havok/Common/Base/Math/Quaternion/hkQuaternionf.h
@@ -7,9 +7,12 @@ using hkQuaternionfParameter = const class hkQuaternionf&;
 class hkQuaternionf {
 public:
     hkQuaternionf() {}  // NOLINT(modernize-use-equals-default)
+    HK_FORCE_INLINE hkQuaternionf(const hkQuaternionf&) = default;
     HK_FORCE_INLINE hkQuaternionf(hkFloat32 ix, hkFloat32 iy, hkFloat32 iz, hkFloat32 r);
     HK_FORCE_INLINE void set(hkFloat32 ix, hkFloat32 iy, hkFloat32 iz, hkFloat32 r);
 
+    HK_FORCE_INLINE hkQuaternionf& operator=(const hkQuaternionf& q);
+
     hkVector4f m_vec;
 };
 
@@ -20,3 +23,8 @@ inline hkQuaternionf::hkQuaternionf(hkFloat32 ix, hkFloat32 iy, hkFloat32 iz, hk
 inline void hkQuaternionf::set(hkFloat32 ix, hkFloat32 iy, hkFloat32 iz, hkFloat32 r) {
     m_vec.set(ix, iy, iz, r);
 }
+
+inline hkQuaternionf& hkQuaternionf::operator=(const hkQuaternionf& q) {
+    m_vec = q.m_vec;
+    return *this;
+}
diff --git a/lib/hkStubs/Havok/Common/Base/Math/Vector/hkVector4f.h b/lib/hkStubs/Havok/Common/Base/Math/Vector/hkVector4f.h
index 4241a235..45eb1a84 100644
--- a/lib/hkStubs/Havok/Common/Base/Math/Vector/hkVector4f.h
+++ b/lib/hkStubs/Havok/Common/Base/Math/Vector/hkVector4f.h
@@ -23,7 +23,7 @@ public:
     HK_FORCE_INLINE hkVector4f() {}
     HK_FORCE_INLINE hkVector4f(hkFloat32 x, hkFloat32 y, hkFloat32 z, hkFloat32 w = 0);
     HK_FORCE_INLINE hkVector4f(const hkVector4f& other);
-    HK_FORCE_INLINE hkVector4f& operator=(hkVector4fParameter) = default;
+    HK_FORCE_INLINE hkVector4f& operator=(hkVector4fParameter other);
 
     // ========== Vector initialization
 
diff --git a/lib/hkStubs/Havok/Common/Base/Math/Vector/hkVector4f.inl b/lib/hkStubs/Havok/Common/Base/Math/Vector/hkVector4f.inl
index ae0fc39e..fa2a10dc 100644
--- a/lib/hkStubs/Havok/Common/Base/Math/Vector/hkVector4f.inl
+++ b/lib/hkStubs/Havok/Common/Base/Math/Vector/hkVector4f.inl
@@ -12,7 +12,14 @@ inline hkVector4f::hkVector4f(hkFloat32 x, hkFloat32 y, hkFloat32 z, hkFloat32 w
     set(x, y, z, w);
 }
 
-inline hkVector4f::hkVector4f(const hkVector4f& other) = default;
+inline hkVector4f::hkVector4f(const hkVector4f& other) {
+    v = other.v;
+}
+
+inline hkVector4f& hkVector4f::operator=(hkVector4fParameter other) {
+    v = other.v;
+    return *this;
+}
 
 inline void hkVector4f::set(hkFloat32 x, hkFloat32 y, hkFloat32 z, hkFloat32 w) {
     v[0] = x;