diff --git a/wpilibc/src/main/native/cpp/spline/SplineHelper.cpp b/wpilibc/src/main/native/cpp/spline/SplineHelper.cpp
index a6b6a6996c..e50e686c17 100644
--- a/wpilibc/src/main/native/cpp/spline/SplineHelper.cpp
+++ b/wpilibc/src/main/native/cpp/spline/SplineHelper.cpp
@@ -63,10 +63,14 @@ std::vector<CubicHermiteSpline> SplineHelper::CubicSplinesFromControlVectors(
         yInitial[1]);
     if (waypoints.size() > 4) {
       for (size_t i = 1; i <= waypoints.size() - 4; ++i) {
-        dx.emplace_back(3 * (waypoints[i + 1].X().to<double>() -
-                             waypoints[i - 1].X().to<double>()));
-        dy.emplace_back(3 * (waypoints[i + 1].Y().to<double>() -
-                             waypoints[i - 1].Y().to<double>()));
+        // dx and dy represent the derivatives of the internal waypoints. The
+        // derivative of the second internal waypoint should involve the third
+        // and first internal waypoint, which have indices of 1 and 3 in the
+        // waypoints list (which contains ALL waypoints).
+        dx.emplace_back(3 * (waypoints[i + 2].X().to<double>() -
+                             waypoints[i].X().to<double>()));
+        dy.emplace_back(3 * (waypoints[i + 2].Y().to<double>() -
+                             waypoints[i].Y().to<double>()));
       }
     }
     dx.emplace_back(3 * (waypoints[waypoints.size() - 1].X().to<double>() -
diff --git a/wpilibj/src/main/java/edu/wpi/first/wpilibj/spline/SplineHelper.java b/wpilibj/src/main/java/edu/wpi/first/wpilibj/spline/SplineHelper.java
index d270554625..73c6aeef61 100644
--- a/wpilibj/src/main/java/edu/wpi/first/wpilibj/spline/SplineHelper.java
+++ b/wpilibj/src/main/java/edu/wpi/first/wpilibj/spline/SplineHelper.java
@@ -145,8 +145,11 @@ public final class SplineHelper {
 
       if (newWaypts.length > 4) {
         for (int i = 1; i <= newWaypts.length - 4; i++) {
-          dx[i] = 3 * (newWaypts[i + 1].getX() - newWaypts[i - 1].getX());
-          dy[i] = 3 * (newWaypts[i + 1].getY() - newWaypts[i - 1].getY());
+          // dx and dy represent the derivatives of the internal waypoints. The derivative
+          // of the second internal waypoint should involve the third and first internal waypoint,
+          // which have indices of 1 and 3 in the newWaypts list (which contains ALL waypoints).
+          dx[i] = 3 * (newWaypts[i + 2].getX() - newWaypts[i].getX());
+          dy[i] = 3 * (newWaypts[i + 2].getY() - newWaypts[i].getY());
         }
       }