diff --git a/lib/hkStubs/Havok/Common/Base/Math/Vector/hkVector4f.h b/lib/hkStubs/Havok/Common/Base/Math/Vector/hkVector4f.h
index 9af511ad..b4504c79 100644
--- a/lib/hkStubs/Havok/Common/Base/Math/Vector/hkVector4f.h
+++ b/lib/hkStubs/Havok/Common/Base/Math/Vector/hkVector4f.h
@@ -105,6 +105,18 @@ public:
     template <int N>
     HK_FORCE_INLINE void setNeg(hkVector4fParameter a);
 
+    /// v[i] = mask[i] ? -a[i] : a[i]
+    HK_FORCE_INLINE void setFlipSign(hkVector4fParameter a, hkVector4fComparisonParameter mask);
+    /// v[i] = signs[i] < 0 ? -a[i] : a[i]
+    HK_FORCE_INLINE void setFlipSign(hkVector4fParameter a, hkVector4fParameter signs);
+    /// v[i] = sign < 0 ? -a[i] : a[i]
+    HK_FORCE_INLINE void setFlipSign(hkVector4fParameter a, hkSimdFloat32Parameter sign);
+
+    /// Whether the sign bit is set. (True for -0.0.)
+    HK_FORCE_INLINE hkVector4fComparison signBitSet() const;
+    /// Whether the sign bit is cleared.
+    HK_FORCE_INLINE hkVector4fComparison signBitClear() const;
+
     // ========== Matrix operations (out-of-line)
 
     void setRotatedDir(const hkMatrix3f& a, hkVector4fParameter b);
diff --git a/lib/hkStubs/Havok/Common/Base/Math/Vector/hkVector4f.inl b/lib/hkStubs/Havok/Common/Base/Math/Vector/hkVector4f.inl
index 88c9379e..b11ce178 100644
--- a/lib/hkStubs/Havok/Common/Base/Math/Vector/hkVector4f.inl
+++ b/lib/hkStubs/Havok/Common/Base/Math/Vector/hkVector4f.inl
@@ -347,6 +347,30 @@ inline void hkVector4f::setNeg(hkVector4fParameter a) {
 #endif
 }
 
+inline void hkVector4f::setFlipSign(hkVector4fParameter a, hkVector4fComparisonParameter mask) {
+    static constexpr m128u signbits = {0x80000000, 0x80000000, 0x80000000, 0x80000000};
+    v = m128u(a.v) ^ (mask.m_mask & signbits);
+}
+
+inline void hkVector4f::setFlipSign(hkVector4fParameter a, hkVector4fParameter signs) {
+    static constexpr m128u signbits = {0x80000000, 0x80000000, 0x80000000, 0x80000000};
+    v = m128u(a.v) ^ (m128u(signs.v) & signbits);
+}
+
+inline void hkVector4f::setFlipSign(hkVector4fParameter a, hkSimdFloat32Parameter sign) {
+    setFlipSign(a, hkVector4fComparison::convert(sign.toQuad()));
+}
+
+inline hkVector4fComparison hkVector4f::signBitSet() const {
+    static constexpr m128u signbits = {0x80000000, 0x80000000, 0x80000000, 0x80000000};
+    return hkVector4fComparison::convert((m128u(v) & signbits) != m128u());
+}
+
+inline hkVector4fComparison hkVector4f::signBitClear() const {
+    static constexpr m128u signbits = {0x80000000, 0x80000000, 0x80000000, 0x80000000};
+    return hkVector4fComparison::convert((m128u(v) & signbits) == m128u());
+}
+
 inline void hkVector4f::_setRotatedDir(const hkMatrix3f& a, hkVector4fParameter b) {
 #ifdef HK_VECTOR4F_AARCH64_NEON
     auto col0 = vmulq_laneq_f32(a.m_col0.v, b.v, 0);