diff --git a/src/libaevol/Fuzzy.cpp b/src/libaevol/Fuzzy.cpp
index fc605b0ecfed3f7a43062c46fe7cc1985a935eeb..f1c71807856e9e155405beecfa894dadf3fee098 100644
--- a/src/libaevol/Fuzzy.cpp
+++ b/src/libaevol/Fuzzy.cpp
@@ -476,12 +476,14 @@ void Fuzzy::clear() {
 
 void Fuzzy::add_point(ProteinConcentration x, ProteinConcentration y)
 {
+  // Don't add a new point if there's already a point at the same x.
   list<Point>::iterator p =
 #ifndef __OPENMP_GPU
       find_if(points_.begin(), points_.end(), [x](Point& q){return q.x > x;});
 #else
       algorithm_cuda::find_if_point_5(points_.begin(), points_.end(), x);
 #endif
+
   if (prev(p)->x == x) {
     prev(p)->y += y;
   } else {