diff --git a/src/HierarchicalSystem.java b/src/HierarchicalSystem.java
index 93cd342..88cb36c 100644
--- a/src/HierarchicalSystem.java
+++ b/src/HierarchicalSystem.java
@@ -138,15 +138,13 @@ public class HierarchicalSystem implements CosmicSystem, MassiveIterable {
             public Massive next() {
                 if (cur != null && cur.hasNext()) return cur.next();
 
-                for (; i < all.length; i++) {
-                    CosmicSystem sys = all[i];
+                while (i < all.length) {
+                    CosmicSystem sys = all[i++];
                     if (sys instanceof NamedBodyForcePair m) {
-                        i++;
                         return m.getBody();
                     } else if (sys instanceof HierarchicalSystem hs) {
                         cur = hs.iterator();
                         if (cur.hasNext()) {
-                            i++;
                             return cur.next();
                         }
                     }
@@ -159,14 +157,14 @@ public class HierarchicalSystem implements CosmicSystem, MassiveIterable {
             public boolean hasNext() {
                 if (cur != null && cur.hasNext()) return true;
 
-                for (; i < all.length; i++) {
+                while (i < all.length) {
                     CosmicSystem sys = all[i];
-                    if (sys instanceof NamedBodyForcePair) {
-                        return true;
-                    } else if (sys instanceof HierarchicalSystem hs) {
+                    if (sys instanceof NamedBodyForcePair) return true;
+                    i++;
+
+                    if (sys instanceof HierarchicalSystem hs) {
                         cur = hs.iterator();
                         if (cur.hasNext()) {
-                            i++;
                             return true;
                         }
                     }