diff --git a/worldedit-core/src/main/java/com/sk89q/worldedit/regions/selector/CylinderRegionSelector.java b/worldedit-core/src/main/java/com/sk89q/worldedit/regions/selector/CylinderRegionSelector.java
index b99142675..19548e348 100644
--- a/worldedit-core/src/main/java/com/sk89q/worldedit/regions/selector/CylinderRegionSelector.java
+++ b/worldedit-core/src/main/java/com/sk89q/worldedit/regions/selector/CylinderRegionSelector.java
@@ -56,6 +56,8 @@ public class CylinderRegionSelector implements RegionSelector, CUIRegion {
 
     protected static final transient NumberFormat NUMBER_FORMAT;
     protected transient CylinderRegion region;
+    protected transient boolean selectedCenter;
+    protected transient boolean selectedRadius;
 
     static {
         NUMBER_FORMAT = (NumberFormat) NumberFormat.getInstance().clone();
@@ -95,6 +97,8 @@ public class CylinderRegionSelector implements RegionSelector, CUIRegion {
             final CylinderRegionSelector cylSelector = (CylinderRegionSelector) oldSelector;
 
             region = new CylinderRegion(cylSelector.region);
+            selectedCenter = cylSelector.selectedCenter;
+            selectedRadius = cylSelector.selectedRadius;
         } else {
             final Region oldRegion;
             try {
@@ -112,6 +116,9 @@ public class CylinderRegionSelector implements RegionSelector, CUIRegion {
 
             region.setMaximumY(Math.max(pos1.getBlockY(), pos2.getBlockY()));
             region.setMinimumY(Math.min(pos1.getBlockY(), pos2.getBlockY()));
+
+            selectedCenter = true;
+            selectedRadius = true;
         }
     }
 
@@ -132,6 +139,9 @@ public class CylinderRegionSelector implements RegionSelector, CUIRegion {
 
         region.setMinimumY(Math.min(minY, maxY));
         region.setMaximumY(Math.max(minY, maxY));
+
+        selectedCenter = true;
+        selectedRadius = true;
     }
 
     @Nullable
@@ -147,7 +157,7 @@ public class CylinderRegionSelector implements RegionSelector, CUIRegion {
 
     @Override
     public boolean selectPrimary(BlockVector3 position, SelectorLimits limits) {
-        if (!region.getCenter().equals(Vector3.ZERO) && position.equals(region.getCenter().toBlockPoint())) {
+        if (selectedCenter && position.equals(region.getCenter().toBlockPoint()) && !selectedRadius) {
             return false;
         }
 
@@ -155,22 +165,26 @@ public class CylinderRegionSelector implements RegionSelector, CUIRegion {
         region.setCenter(position.toBlockVector2());
         region.setY(position.getBlockY());
 
+        selectedCenter = true;
+        selectedRadius = false;
+
         return true;
     }
 
     @Override
     public boolean selectSecondary(BlockVector3 position, SelectorLimits limits) {
-        Vector3 center = region.getCenter();
-        if (center.equals(Vector3.ZERO)) {
+        if (!selectedCenter) {
             return true;
         }
 
-        final Vector2 diff = position.toVector3().subtract(center).toVector2();
+        final Vector2 diff = position.toVector3().subtract(region.getCenter()).toVector2();
         final Vector2 minRadius = diff.getMaximum(diff.multiply(-1.0));
         region.extendRadius(minRadius);
 
         region.setY(position.getBlockY());
 
+        selectedRadius = true;
+
         return true;
     }
 
@@ -183,9 +197,7 @@ public class CylinderRegionSelector implements RegionSelector, CUIRegion {
 
     @Override
     public void explainSecondarySelection(Actor player, LocalSession session, BlockVector3 pos) {
-        Vector3 center = region.getCenter();
-
-        if (!center.equals(Vector3.ZERO)) {
+        if (selectedCenter) {
             player.print(Caption.of(
                     "worldedit.selection.cylinder.explain.secondary",
                     TextComponent.of(NUMBER_FORMAT.format(region.getRadius().getX())),
@@ -230,7 +242,8 @@ public class CylinderRegionSelector implements RegionSelector, CUIRegion {
 
     @Override
     public boolean isDefined() {
-        return !region.getRadius().equals(Vector2.ZERO);
+        // selectedCenter is implied by selectedRadius
+        return selectedRadius;
     }
 
     @Override
diff --git a/worldedit-core/src/main/java/com/sk89q/worldedit/regions/selector/EllipsoidRegionSelector.java b/worldedit-core/src/main/java/com/sk89q/worldedit/regions/selector/EllipsoidRegionSelector.java
index 52a0921e5..fd7521861 100644
--- a/worldedit-core/src/main/java/com/sk89q/worldedit/regions/selector/EllipsoidRegionSelector.java
+++ b/worldedit-core/src/main/java/com/sk89q/worldedit/regions/selector/EllipsoidRegionSelector.java
@@ -52,6 +52,7 @@ public class EllipsoidRegionSelector implements RegionSelector, CUIRegion {
 
     protected transient EllipsoidRegion region;
     protected transient boolean started = false;
+    protected transient boolean selectedRadius = false;
 
     /**
      * Create a new selector with a {@code null} world.
@@ -81,6 +82,7 @@ public class EllipsoidRegionSelector implements RegionSelector, CUIRegion {
 
             region = new EllipsoidRegion(ellipsoidRegionSelector.getIncompleteRegion());
             started = ellipsoidRegionSelector.started;
+            selectedRadius = ellipsoidRegionSelector.selectedRadius;
         } else {
             Region oldRegion;
             try {
@@ -96,6 +98,7 @@ public class EllipsoidRegionSelector implements RegionSelector, CUIRegion {
             region.setCenter(center);
             region.setRadius(pos2.subtract(center).toVector3());
             started = true;
+            selectedRadius = true;
         }
     }
 
@@ -111,6 +114,9 @@ public class EllipsoidRegionSelector implements RegionSelector, CUIRegion {
 
         region.setCenter(center);
         region.setRadius(radius);
+
+        started = true;
+        selectedRadius = true;
     }
 
     @Nullable
@@ -126,13 +132,14 @@ public class EllipsoidRegionSelector implements RegionSelector, CUIRegion {
 
     @Override
     public boolean selectPrimary(BlockVector3 position, SelectorLimits limits) {
-        if (position.equals(region.getCenter().toBlockPoint()) && region.getRadius().lengthSq() == 0) {
+        if (started && position.equals(region.getCenter().toBlockPoint()) && !selectedRadius) {
             return false;
         }
 
         region.setCenter(position);
         region.setRadius(Vector3.ZERO);
         started = true;
+        selectedRadius = false;
 
         return true;
     }
@@ -146,6 +153,9 @@ public class EllipsoidRegionSelector implements RegionSelector, CUIRegion {
         final Vector3 diff = position.toVector3().subtract(region.getCenter());
         final Vector3 minRadius = diff.getMaximum(diff.multiply(-1.0));
         region.extendRadius(minRadius);
+
+        selectedRadius = true;
+
         return true;
     }
 
@@ -192,7 +202,8 @@ public class EllipsoidRegionSelector implements RegionSelector, CUIRegion {
 
     @Override
     public boolean isDefined() {
-        return started && region.getRadius().lengthSq() > 0;
+        // started implied by selectedRadius
+        return selectedRadius;
     }
 
     @Override
diff --git a/worldedit-core/src/main/java/com/sk89q/worldedit/regions/selector/SphereRegionSelector.java b/worldedit-core/src/main/java/com/sk89q/worldedit/regions/selector/SphereRegionSelector.java
index 67d58242c..6b801c25c 100644
--- a/worldedit-core/src/main/java/com/sk89q/worldedit/regions/selector/SphereRegionSelector.java
+++ b/worldedit-core/src/main/java/com/sk89q/worldedit/regions/selector/SphereRegionSelector.java
@@ -59,9 +59,11 @@ public class SphereRegionSelector extends EllipsoidRegionSelector {
      */
     public SphereRegionSelector(RegionSelector oldSelector) {
         super(oldSelector);
-        final Vector3 radius = region.getRadius();
-        final double radiusScalar = Math.max(Math.max(radius.getX(), radius.getY()), radius.getZ());
-        region.setRadius(Vector3.at(radiusScalar, radiusScalar, radiusScalar));
+        if (selectedRadius) {
+            final Vector3 radius = region.getRadius();
+            final double radiusScalar = Math.max(Math.max(radius.getX(), radius.getY()), radius.getZ());
+            region.setRadius(Vector3.at(radiusScalar, radiusScalar, radiusScalar));
+        }
     }
 
     /**
@@ -84,6 +86,8 @@ public class SphereRegionSelector extends EllipsoidRegionSelector {
         final double radiusScalar = Math.ceil(position.toVector3().distance(region.getCenter()));
         region.setRadius(Vector3.at(radiusScalar, radiusScalar, radiusScalar));
 
+        selectedRadius = true;
+
         return true;
     }