diff --git a/package-lock.json b/package-lock.json
index 9418aee..4a229cf 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "curve-interpolator",
-  "version": "3.1.0-beta.1",
+  "version": "3.1.0",
   "lockfileVersion": 2,
   "requires": true,
   "packages": {
     "": {
       "name": "curve-interpolator",
-      "version": "3.1.0-beta.1",
+      "version": "3.1.0",
       "license": "MIT",
       "devDependencies": {
         "@rollup/plugin-node-resolve": "^15.0.1",
diff --git a/package.json b/package.json
index c38e2c0..ada7bb4 100644
--- a/package.json
+++ b/package.json
@@ -1,7 +1,7 @@
 {
   "private": false,
   "name": "curve-interpolator",
-  "version": "3.1.0",
+  "version": "3.1.1",
   "description": "Interpolate values on a Cardinal/Catmull-Rom spline curve",
   "repository": "https://github.com/kjerandp/curve-interpolator",
   "bugs": {
diff --git a/src/core/spline-segment.ts b/src/core/spline-segment.ts
index 3db3e1e..f5b70ca 100644
--- a/src/core/spline-segment.ts
+++ b/src/core/spline-segment.ts
@@ -63,8 +63,9 @@ export function calculateCoefficients(p0: Vector, p1:Vector, p2:Vector, p3:Vecto
 
     const a = (2 * v1 - 2 * v2 + u + v);
     const b = (-3 * v1 + 3 * v2 - 2 * u - v);
+    const c = u;
     const d = v1;
-    coefficientsList[k] = [a, b, u, d];
+    coefficientsList[k] = [a, b, c, d];
   }
   return coefficientsList;
 }
diff --git a/src/curve-interpolator.spec.ts b/src/curve-interpolator.spec.ts
index e11d6d3..56c7a8f 100644
--- a/src/curve-interpolator.spec.ts
+++ b/src/curve-interpolator.spec.ts
@@ -92,6 +92,37 @@ describe('curve-interpolator.ts', () => {
 
   });
 
+  it('should be able to lookup extrema on curve', () => {
+    const interp = new CurveInterpolator([[187.7, 113.4], [930, 821.62], [1620, 1330.82], [2310, 1621.24]], { tension: 0.75, alpha: 0 });
+
+    // expect one solution for the end-points in this data
+    let actual = interp.getIntersects(187.7, 0, 0) as number[];
+    expect(actual.length).to.eq(1);
+    
+    actual = interp.getIntersects(2310, 0, 0) as number[];
+    expect(actual.length).to.eq(1);
+
+    //from start of curve
+    actual = interp.getIntersects(187.7, 0, 1) as number[];
+    expect(actual).to.not.be.null;
+    expect(actual[1]).to.be.closeTo(113.4, EPS);
+
+    actual = interp.getIntersects(2310, 0, 1) as number[];
+    expect(actual).to.not.be.null;
+    expect(actual[1]).to.be.closeTo(1621.24, EPS);
+    
+    // from end of curve
+    actual = interp.getIntersects(187.7, 0, -1) as number[];
+    expect(actual).to.not.be.null;
+    expect(actual[1]).to.be.closeTo(113.4, EPS);
+
+    actual = interp.getIntersects(2310, 0, -1) as number[];
+    expect(actual).to.not.be.null;
+    expect(actual[1]).to.be.closeTo(1621.24, EPS);
+
+
+  });
+
   it('should be able to get bounds of curve', () => {
     const interp = new CurveInterpolator(points, { tension: 0, alpha: 0 });
 
diff --git a/src/curve-interpolator.ts b/src/curve-interpolator.ts
index b410546..4e6c1a9 100644
--- a/src/curve-interpolator.ts
+++ b/src/curve-interpolator.ts
@@ -507,7 +507,6 @@ export default class CurveInterpolator {
         else if (max >= 0) ts.sort((a, b) => a - b);
 
         for (let j = 0; j < ts.length; j++) {
-          if (ts[j] === 0 && i > 0) continue; // avoid duplicate (0 would be found as 1 in previous iteration)
           const nt = (ts[j] + idx) / nPoints; // normalize t
           solutions.add(nt);