diff --git a/thomson-problem.js b/thomson-problem.js
index 3843784..3dba5c2 100644
--- a/thomson-problem.js
+++ b/thomson-problem.js
@@ -24,9 +24,9 @@ function move_particles(particles, force_constant) {
       } else {
         ai = displacement.copy().normalize();
         aj = ai.copy().mult(-1);
+        ai.mult(ai_mag);
+        aj.mult(aj_mag);
       }
-      ai.mult(ai_mag);
-      aj.mult(aj_mag);
       project_onto_plane(ai, particles[i].position);
       project_onto_plane(aj, particles[j].position);
       particles[i].acceleration.add(ai);