diff --git a/lucene/spatial3d/src/java/org/apache/lucene/spatial3d/geom/GeoComplexPolygon.java b/lucene/spatial3d/src/java/org/apache/lucene/spatial3d/geom/GeoComplexPolygon.java
index d11fb79d07c..f64755c0199 100644
--- a/lucene/spatial3d/src/java/org/apache/lucene/spatial3d/geom/GeoComplexPolygon.java
+++ b/lucene/spatial3d/src/java/org/apache/lucene/spatial3d/geom/GeoComplexPolygon.java
@@ -195,7 +195,7 @@ class GeoComplexPolygon extends GeoBasePolygon {
     }
     
     // If we're right on top of any of the test planes, we navigate solely on that plane.
-    if (testPointFixedYPlane.evaluateIsZero(x, y, z)) {
+    if (testPointFixedYAbovePlane != null && testPointFixedYBelowPlane != null && testPointFixedYPlane.evaluateIsZero(x, y, z)) {
       // Use the XZ plane exclusively.
       final CountingEdgeIterator crossingEdgeIterator = createLinearCrossingEdgeIterator(testPointFixedYPlane, testPointFixedYAbovePlane, testPointFixedYBelowPlane, x, y, z);
       // Traverse our way from the test point to the check point.  Use the y tree because that's fixed.
@@ -204,7 +204,7 @@ class GeoComplexPolygon extends GeoBasePolygon {
         return true;
       }
       return ((crossingEdgeIterator.getCrossingCount() & 1) == 0)?testPointInSet:!testPointInSet;
-    } else if (testPointFixedXPlane.evaluateIsZero(x, y, z)) {
+    } else if (testPointFixedXAbovePlane != null && testPointFixedXBelowPlane != null && testPointFixedXPlane.evaluateIsZero(x, y, z)) {
       // Use the YZ plane exclusively.
       final CountingEdgeIterator crossingEdgeIterator = createLinearCrossingEdgeIterator(testPointFixedXPlane, testPointFixedXAbovePlane, testPointFixedXBelowPlane, x, y, z);
       // Traverse our way from the test point to the check point.  Use the x tree because that's fixed.
@@ -213,7 +213,7 @@ class GeoComplexPolygon extends GeoBasePolygon {
         return true;
       }
       return ((crossingEdgeIterator.getCrossingCount() & 1) == 0)?testPointInSet:!testPointInSet;
-    } else if (testPointFixedZPlane.evaluateIsZero(x, y, z)) {
+    } else if (testPointFixedZAbovePlane != null && testPointFixedZBelowPlane != null && testPointFixedZPlane.evaluateIsZero(x, y, z)) {
       final CountingEdgeIterator crossingEdgeIterator = createLinearCrossingEdgeIterator(testPointFixedZPlane, testPointFixedZAbovePlane, testPointFixedZBelowPlane, x, y, z);
       // Traverse our way from the test point to the check point.  Use the z tree because that's fixed.
       if (!zTree.traverse(crossingEdgeIterator, testPoint.z)) {
@@ -221,6 +221,8 @@ class GeoComplexPolygon extends GeoBasePolygon {
         return true;
       }
       return ((crossingEdgeIterator.getCrossingCount() & 1) == 0)?testPointInSet:!testPointInSet;
+    } else if (testPointFixedYPlane.evaluateIsZero(x, y, z) || testPointFixedXPlane.evaluateIsZero(x, y, z) || testPointFixedZPlane.evaluateIsZero(x, y, z)) {
+      throw new IllegalArgumentException("Can't compute isWithin for specified point");
     } else {
 
       // This is the expensive part!!
@@ -903,6 +905,9 @@ class GeoComplexPolygon extends GeoBasePolygon {
       this.plane = plane;
       this.abovePlane = abovePlane;
       this.belowPlane = belowPlane;
+      if (plane.isNumericallyIdentical(testPoint)) {
+        throw new IllegalArgumentException("Plane vector identical to testpoint vector");
+      }
       // It doesn't matter which 1/2 of the world we choose, but we must choose only one.
       this.bound = new SidedPlane(plane, testPoint);
       this.thePointX = thePointX;
diff --git a/lucene/spatial3d/src/test/org/apache/lucene/spatial3d/geom/GeoPolygonTest.java b/lucene/spatial3d/src/test/org/apache/lucene/spatial3d/geom/GeoPolygonTest.java
index b5c18cf1f93..ee15ec48382 100755
--- a/lucene/spatial3d/src/test/org/apache/lucene/spatial3d/geom/GeoPolygonTest.java
+++ b/lucene/spatial3d/src/test/org/apache/lucene/spatial3d/geom/GeoPolygonTest.java
@@ -1450,7 +1450,6 @@ shape:
     assertTrue(polygon.isWithin(point1) == largePolygon.isWithin(point1));
   }
 
-  @Ignore
   @Test
   public void testComplexPolygonDegeneratedVector() {
     List<GeoPoint> points = new ArrayList<>();