diff --git a/libraries/animation/src/AnimInverseKinematics.cpp b/libraries/animation/src/AnimInverseKinematics.cpp
index 2fd52ee036..095e8333ee 100644
--- a/libraries/animation/src/AnimInverseKinematics.cpp
+++ b/libraries/animation/src/AnimInverseKinematics.cpp
@@ -22,6 +22,7 @@
 #include "AnimationLogging.h"
 #include "CubicHermiteSpline.h"
 #include "AnimUtil.h"
+#include "AnimSkeleton.h"
 
 static const int MAX_TARGET_MARKERS = 30;
 static const float JOINT_CHAIN_INTERP_TIME = 0.5f;
@@ -66,7 +67,7 @@ AnimInverseKinematics::IKTargetVar::IKTargetVar(const QString& jointNameIn, cons
     poleVectorVar(poleVectorVarIn),
     weight(weightIn),
     numFlexCoefficients(flexCoefficientsIn.size()),
-    jointIndex(-1)
+    jointIndex(AnimSkeleton::INVALID_JOINT_INDEX)
 {
     numFlexCoefficients = std::min(numFlexCoefficients, (size_t)MAX_FLEX_COEFFICIENTS);
     for (size_t i = 0; i < numFlexCoefficients; i++) {
@@ -172,14 +173,14 @@ bool debounceJointWarnings() {
 
 void AnimInverseKinematics::computeTargets(const AnimVariantMap& animVars, std::vector<IKTarget>& targets, const AnimPoseVec& underPoses) {
 
-    _hipsTargetIndex = -1;
+    _hipsTargetIndex = AnimSkeleton::INVALID_JOINT_INDEX;
 
     targets.reserve(_targetVarVec.size());
 
     for (auto& targetVar : _targetVarVec) {
 
         // update targetVar jointIndex cache
-        if (targetVar.jointIndex == -1) {
+        if (targetVar.jointIndex == AnimSkeleton::INVALID_JOINT_INDEX) {
             int jointIndex = _skeleton->nameToJointIndex(targetVar.jointName);
             if (jointIndex >= 0) {
                 // this targetVar has a valid joint --> cache the indices
@@ -190,7 +191,7 @@ void AnimInverseKinematics::computeTargets(const AnimVariantMap& animVars, std::
         }
 
         IKTarget target;
-        if (targetVar.jointIndex != -1) {
+        if (targetVar.jointIndex != AnimSkeleton::INVALID_JOINT_INDEX) {
             target.setType(animVars.lookup(targetVar.typeVar, (int)IKTarget::Type::RotationAndPosition));
             target.setIndex(targetVar.jointIndex);
             if (target.getType() != IKTarget::Type::Unknown) {
@@ -329,7 +330,7 @@ void AnimInverseKinematics::solve(const AnimContext& context, const std::vector<
         // update the absolutePoses
         for (int i = 0; i < (int)_relativePoses.size(); ++i) {
             auto parentIndex = _skeleton->getParentIndex((int)i);
-            if (parentIndex != -1) {
+            if (parentIndex != AnimSkeleton::INVALID_JOINT_INDEX) {
                 absolutePoses[i] = absolutePoses[parentIndex] * _relativePoses[i];
             }
         }
@@ -351,12 +352,12 @@ void AnimInverseKinematics::solve(const AnimContext& context, const std::vector<
     // finally set the relative rotation of each tip to agree with absolute target rotation
     for (auto& target: targets) {
         int tipIndex = target.getIndex();
-        int parentIndex = (tipIndex >= 0) ? _skeleton->getParentIndex(tipIndex) : -1;
+        int parentIndex = (tipIndex >= 0) ? _skeleton->getParentIndex(tipIndex) : AnimSkeleton::INVALID_JOINT_INDEX;
         int chainIndex = targetToChainMap[tipIndex];
         bool needsInterpolation = _prevJointChainInfoVec[chainIndex].timer > 0.0f;
         float alpha = needsInterpolation ? getInterpolationAlpha(_prevJointChainInfoVec[chainIndex].timer) : 0.0f;
         // update rotationOnly targets that don't lie on the ik chain of other ik targets.
-        if (parentIndex != -1 && !_rotationAccumulators[tipIndex].isDirty() && 
+        if (parentIndex != AnimSkeleton::INVALID_JOINT_INDEX && !_rotationAccumulators[tipIndex].isDirty() && 
             (target.getType() == IKTarget::Type::RotationOnly || target.getType() == IKTarget::Type::Unknown)) {
             if (target.getType() == IKTarget::Type::RotationOnly) {
                 const glm::quat& targetRotation = target.getRotation();
@@ -434,11 +435,11 @@ void AnimInverseKinematics::solveTargetWithCCD(const AnimContext& context, const
 
     int tipIndex = target.getIndex();
     int pivotIndex = _skeleton->getParentIndex(tipIndex);
-    if (pivotIndex == -1 || pivotIndex == _hipsIndex) {
+    if (pivotIndex == AnimSkeleton::INVALID_JOINT_INDEX || pivotIndex == _hipsIndex) {
         return;
     }
     int pivotsParentIndex = _skeleton->getParentIndex(pivotIndex);
-    if (pivotsParentIndex == -1) {
+    if (pivotsParentIndex == AnimSkeleton::INVALID_JOINT_INDEX) {
         // TODO?: handle case where tip's parent is root?
         return;
     }
@@ -485,7 +486,7 @@ void AnimInverseKinematics::solveTargetWithCCD(const AnimContext& context, const
     chainDepth++;
 
     // descend toward root, pivoting each joint to get tip closer to target position
-    while (pivotIndex != _hipsIndex && pivotsParentIndex != -1) {
+    while (pivotIndex != _hipsIndex && pivotsParentIndex != AnimSkeleton::INVALID_JOINT_INDEX) {
 
         assert(chainDepth < jointChainInfoOut.jointInfoVec.size());
 
@@ -579,12 +580,12 @@ void AnimInverseKinematics::solveTargetWithCCD(const AnimContext& context, const
     if (target.getPoleVectorEnabled()) {
         int topJointIndex = target.getIndex();
         int midJointIndex = _skeleton->getParentIndex(topJointIndex);
-        if (midJointIndex != -1) {
+        if (midJointIndex != AnimSkeleton::INVALID_JOINT_INDEX) {
             int baseJointIndex = _skeleton->getParentIndex(midJointIndex);
-            if (baseJointIndex != -1) {
+            if (baseJointIndex != AnimSkeleton::INVALID_JOINT_INDEX) {
                 int baseParentJointIndex = _skeleton->getParentIndex(baseJointIndex);
                 AnimPose topPose, midPose, basePose;
-                int topChainIndex = -1, baseChainIndex = -1;
+                int topChainIndex = AnimSkeleton::INVALID_JOINT_INDEX, baseChainIndex = AnimSkeleton::INVALID_JOINT_INDEX;
                 const size_t MAX_CHAIN_DEPTH = 30;
                 AnimPose postAbsPoses[MAX_CHAIN_DEPTH];
                 AnimPose accum = absolutePoses[_hipsIndex];
@@ -756,7 +757,7 @@ void AnimInverseKinematics::computeAndCacheSplineJointInfosForIKTarget(const Ani
 
     int index = target.getIndex();
     int endIndex = _skeleton->getParentIndex(_hipsIndex);
-    while (index != endIndex) {
+    while (index != endIndex && index != AnimSkeleton::INVALID_JOINT_INDEX) {
         AnimPose defaultPose = _skeleton->getAbsoluteDefaultPose(index);
 
         float ratio = glm::dot(defaultPose.trans() - basePose.trans(), baseToTipNormal) / baseToTipLength;
@@ -1460,7 +1461,7 @@ void AnimInverseKinematics::setSkeletonInternal(AnimSkeleton::ConstPointer skele
 
     // invalidate all targetVars
     for (auto& targetVar: _targetVarVec) {
-        targetVar.jointIndex = -1;
+        targetVar.jointIndex = AnimSkeleton::INVALID_JOINT_INDEX;
     }
 
     for (auto& accumulator: _rotationAccumulators) {
@@ -1480,18 +1481,18 @@ void AnimInverseKinematics::setSkeletonInternal(AnimSkeleton::ConstPointer skele
         if (_hipsIndex >= 0) {
             _hipsParentIndex = _skeleton->getParentIndex(_hipsIndex);
         } else {
-            _hipsParentIndex = -1;
+            _hipsParentIndex = AnimSkeleton::INVALID_JOINT_INDEX;
         }
 
         _leftHandIndex = _skeleton->nameToJointIndex("LeftHand");
         _rightHandIndex = _skeleton->nameToJointIndex("RightHand");
     } else {
         clearConstraints();
-        _headIndex = -1;
-        _hipsIndex = -1;
-        _hipsParentIndex = -1;
-        _leftHandIndex = -1;
-        _rightHandIndex = -1;
+        _headIndex = AnimSkeleton::INVALID_JOINT_INDEX;
+        _hipsIndex = AnimSkeleton::INVALID_JOINT_INDEX;
+        _hipsParentIndex = AnimSkeleton::INVALID_JOINT_INDEX;
+        _leftHandIndex = AnimSkeleton::INVALID_JOINT_INDEX;
+        _rightHandIndex = AnimSkeleton::INVALID_JOINT_INDEX;
     }
 }
 
@@ -1531,7 +1532,7 @@ void AnimInverseKinematics::debugDrawRelativePoses(const AnimContext& context) c
 
         // draw line to parent
         int parentIndex = _skeleton->getParentIndex(i);
-        if (parentIndex != -1) {
+        if (parentIndex != AnimSkeleton::INVALID_JOINT_INDEX) {
             glm::vec3 parentPos = transformPoint(geomToWorldMatrix, poses[parentIndex].trans());
             DebugDraw::getInstance().drawRay(pos, parentPos, GRAY);
         }
@@ -1580,7 +1581,7 @@ void AnimInverseKinematics::debugDrawIKChain(const JointChainInfo& jointChainInf
             DebugDraw::getInstance().drawRay(pos, pos + AXIS_LENGTH * zAxis, BLUE);
 
             // draw line to parent
-            if (parentIndex != -1) {
+            if (parentIndex != AnimSkeleton::INVALID_JOINT_INDEX) {
                 glm::vec3 parentPos = transformPoint(geomToWorldMatrix, poses[parentIndex].trans());
                 glm::vec4 color = GRAY;
 
@@ -1629,13 +1630,13 @@ void AnimInverseKinematics::debugDrawConstraints(const AnimContext& context) con
 
             // draw line to parent
             int parentIndex = _skeleton->getParentIndex(i);
-            if (parentIndex != -1) {
+            if (parentIndex != AnimSkeleton::INVALID_JOINT_INDEX) {
                 glm::vec3 parentPos = transformPoint(geomToWorldMatrix, poses[parentIndex].trans());
                 DebugDraw::getInstance().drawRay(pos, parentPos, GRAY);
             }
 
             glm::quat parentAbsRot;
-            if (parentIndex != -1) {
+            if (parentIndex != AnimSkeleton::INVALID_JOINT_INDEX) {
                 parentAbsRot = poses[parentIndex].rot();
             }
 
@@ -1733,7 +1734,7 @@ void AnimInverseKinematics::preconditionRelativePosesToAvoidLimbLock(const AnimC
     const float MIN_AXIS_LENGTH = 1.0e-4f;
 
     for (auto& target : targets) {
-        if (target.getIndex() != -1 && target.getType() == IKTarget::Type::RotationAndPosition) {
+        if (target.getIndex() != AnimSkeleton::INVALID_JOINT_INDEX && target.getType() == IKTarget::Type::RotationAndPosition) {
             for (int i = 0; i < NUM_LIMBS; i++) {
                 if (limbs[i].first == target.getIndex()) {
                     int tipIndex = limbs[i].first;
diff --git a/libraries/animation/src/AnimSkeleton.cpp b/libraries/animation/src/AnimSkeleton.cpp
index b26d00d8d0..bd338aae4a 100644
--- a/libraries/animation/src/AnimSkeleton.cpp
+++ b/libraries/animation/src/AnimSkeleton.cpp
@@ -66,7 +66,7 @@ int AnimSkeleton::nameToJointIndex(const QString& jointName) const {
     if (_jointIndicesByName.end() != itr) {
         return itr.value();
     }
-    return -1;
+    return INVALID_JOINT_INDEX;
 }
 
 int AnimSkeleton::getNumJoints() const {
@@ -80,7 +80,7 @@ int AnimSkeleton::getChainDepth(int jointIndex) const {
         do {
             chainDepth++;
             index = _parentIndices[index];
-        } while (index != -1);
+        } while (index != INVALID_JOINT_INDEX);
         return chainDepth;
     } else {
         return 0;
@@ -108,7 +108,7 @@ const AnimPose& AnimSkeleton::getPostRotationPose(int jointIndex) const {
 std::vector<int> AnimSkeleton::getChildrenOfJoint(int jointIndex) const {
     // Children and grandchildren, etc.
     std::vector<int> result;
-    if (jointIndex != -1) {
+    if (jointIndex != INVALID_JOINT_INDEX) {
         for (int i = jointIndex + 1; i < (int)_parentIndices.size(); i++) {
             if (_parentIndices[i] == jointIndex || (std::find(result.begin(), result.end(), _parentIndices[i]) != result.end())) {
                 result.push_back(i);
@@ -135,7 +135,7 @@ void AnimSkeleton::convertRelativePosesToAbsolute(AnimPoseVec& poses) const {
     int lastIndex = std::min((int)poses.size(), _jointsSize);
     for (int i = 0; i < lastIndex; ++i) {
         int parentIndex = _parentIndices[i];
-        if (parentIndex != -1) {
+        if (parentIndex != INVALID_JOINT_INDEX) {
             poses[i] = poses[parentIndex] * poses[i];
         }
     }
@@ -146,7 +146,7 @@ void AnimSkeleton::convertAbsolutePosesToRelative(AnimPoseVec& poses) const {
     int lastIndex = std::min((int)poses.size(), _jointsSize);
     for (int i = lastIndex - 1; i >= 0; --i) {
         int parentIndex = _parentIndices[i];
-        if (parentIndex != -1) {
+        if (parentIndex != INVALID_JOINT_INDEX) {
             poses[i] = poses[parentIndex].inverse() * poses[i];
         }
     }
@@ -157,7 +157,7 @@ void AnimSkeleton::convertRelativeRotationsToAbsolute(std::vector<glm::quat>& ro
     int lastIndex = std::min((int)rotations.size(), _jointsSize);
     for (int i = 0; i < lastIndex; ++i) {
         int parentIndex = _parentIndices[i];
-        if (parentIndex != -1) {
+        if (parentIndex != INVALID_JOINT_INDEX) {
             rotations[i] = rotations[parentIndex] * rotations[i];
         }
     }
@@ -168,7 +168,7 @@ void AnimSkeleton::convertAbsoluteRotationsToRelative(std::vector<glm::quat>& ro
     int lastIndex = std::min((int)rotations.size(), _jointsSize);
     for (int i = lastIndex - 1; i >= 0; --i) {
         int parentIndex = _parentIndices[i];
-        if (parentIndex != -1) {
+        if (parentIndex != INVALID_JOINT_INDEX) {
             rotations[i] = glm::inverse(rotations[parentIndex]) * rotations[i];
         }
     }
@@ -280,7 +280,7 @@ void AnimSkeleton::buildSkeletonFromJoints(const std::vector<HFMJoint>& joints,
             // so we can restore them after a future mirror operation
             _nonMirroredIndices.push_back(i);
         }
-        int mirrorJointIndex = -1;
+        int mirrorJointIndex = INVALID_JOINT_INDEX;
         if (_joints[i].name.startsWith("Left")) {
             QString mirrorJointName = QString(_joints[i].name).replace(0, 4, "Right");
             mirrorJointIndex = nameToJointIndex(mirrorJointName);
@@ -350,7 +350,7 @@ std::vector<int> AnimSkeleton::lookUpJointIndices(const std::vector<QString>& jo
     result.reserve(jointNames.size());
     for (auto& name : jointNames) {
         int index = nameToJointIndex(name);
-        if (index == -1) {
+        if (index == INVALID_JOINT_INDEX) {
             qWarning(animation) << "AnimSkeleton::lookUpJointIndices(): could not find bone with name " << name;
         }
         result.push_back(index);
diff --git a/libraries/animation/src/AnimSkeleton.h b/libraries/animation/src/AnimSkeleton.h
index efc1c1599f..e36ceb4042 100644
--- a/libraries/animation/src/AnimSkeleton.h
+++ b/libraries/animation/src/AnimSkeleton.h
@@ -30,6 +30,8 @@ public:
     const QString& getJointName(int jointIndex) const;
     int getNumJoints() const;
     int getChainDepth(int jointIndex) const;
+    
+    static const int INVALID_JOINT_INDEX { -1 };
 
     // the default poses are the orientations of the joints on frame 0.
     const AnimPose& getRelativeDefaultPose(int jointIndex) const;