diff --git a/CHANGES.md b/CHANGES.md
index d36067da186d..0bdb0ce31a75 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -15,6 +15,7 @@ Change Log
 * Fixed an issue where some ground polygons crossing the Prime Meridian would have incorrect bounding rectangles. [#7533](https://github.com/AnalyticalGraphicsInc/cesium/pull/7533)
 * Fixed an issue where polygons on terrain using rhumb lines where being rendered incorrectly. [#7538](https://github.com/AnalyticalGraphicsInc/cesium/pulls/7538)
 * Fixed an issue with `EllipsoidRhumbLines.findIntersectionWithLongitude` when longitude was IDL. [#7551](https://github.com/AnalyticalGraphicsInc/cesium/issues/7551)
+* Fixed an issue with ground polylines on globes that use ellipsoids other than WGS84. [#7552](https://github.com/AnalyticalGraphicsInc/cesium/issues/7552)
 
 ### 1.54 - 2019-02-01
 
diff --git a/Source/Core/GroundPolylineGeometry.js b/Source/Core/GroundPolylineGeometry.js
index d950f2296b27..a5d21e7b9ef1 100644
--- a/Source/Core/GroundPolylineGeometry.js
+++ b/Source/Core/GroundPolylineGeometry.js
@@ -331,16 +331,9 @@ define([
         var scene3DOnly = (array[index++] === 1.0);
 
         if (!defined(result)) {
-            var geometry = new GroundPolylineGeometry({
-                positions : positions,
-                granularity : granularity,
-                loop : loop,
-                arcType : arcType,
-                ellipsoid : ellipsoid
+            result = new GroundPolylineGeometry({
+                positions : positions
             });
-            geometry._projectionIndex = projectionIndex;
-            geometry._scene3DOnly = scene3DOnly;
-            return geometry;
         }
 
         result._positions = positions;
diff --git a/Specs/Core/GroundPolylineGeometrySpec.js b/Specs/Core/GroundPolylineGeometrySpec.js
index b41332a997f3..e19454ff9358 100644
--- a/Specs/Core/GroundPolylineGeometrySpec.js
+++ b/Specs/Core/GroundPolylineGeometrySpec.js
@@ -530,7 +530,7 @@ defineSuite([
             granularity : 10.0 // no interpolative subdivision
         });
         groundPolylineGeometry._scene3DOnly = true;
-        GroundPolylineGeometry.setProjectionAndEllipsoid(groundPolylineGeometry, new WebMercatorProjection(Ellipsoid.WGS84));
+        GroundPolylineGeometry.setProjectionAndEllipsoid(groundPolylineGeometry, new WebMercatorProjection(Ellipsoid.UNIT_SPHERE));
 
         var packedArray = [0];
         GroundPolylineGeometry.pack(groundPolylineGeometry, packedArray, 1);
@@ -548,11 +548,38 @@ defineSuite([
         expect(Cartesian3.equals(scratchPositions[1], groundPolylineGeometry._positions[1])).toBe(true);
         expect(scratch.loop).toBe(true);
         expect(scratch.granularity).toEqual(10.0);
-        expect(scratch._ellipsoid.equals(Ellipsoid.WGS84)).toBe(true);
+        expect(scratch._ellipsoid.equals(Ellipsoid.UNIT_SPHERE)).toBe(true);
         expect(scratch._scene3DOnly).toBe(true);
         expect(scratch._projectionIndex).toEqual(1);
     });
 
+    it('can unpack onto a new instance', function() {
+        var groundPolylineGeometry = new GroundPolylineGeometry({
+            positions : Cartesian3.fromDegreesArray([
+                -1.0, 0.0,
+                1.0, 0.0
+            ]),
+            loop : true,
+            granularity : 10.0 // no interpolative subdivision
+        });
+        groundPolylineGeometry._scene3DOnly = true;
+        GroundPolylineGeometry.setProjectionAndEllipsoid(groundPolylineGeometry, new WebMercatorProjection(Ellipsoid.UNIT_SPHERE));
+
+        var packedArray = [0];
+        GroundPolylineGeometry.pack(groundPolylineGeometry, packedArray, 1);
+        var result = GroundPolylineGeometry.unpack(packedArray, 1);
+
+        var scratchPositions = result._positions;
+        expect(scratchPositions.length).toEqual(2);
+        expect(Cartesian3.equals(scratchPositions[0], groundPolylineGeometry._positions[0])).toBe(true);
+        expect(Cartesian3.equals(scratchPositions[1], groundPolylineGeometry._positions[1])).toBe(true);
+        expect(result.loop).toBe(true);
+        expect(result.granularity).toEqual(10.0);
+        expect(result._ellipsoid.equals(Ellipsoid.UNIT_SPHERE)).toBe(true);
+        expect(result._scene3DOnly).toBe(true);
+        expect(result._projectionIndex).toEqual(1);
+    });
+
     it('provides a method for setting projection and ellipsoid', function() {
         var groundPolylineGeometry = new GroundPolylineGeometry({
             positions : Cartesian3.fromDegreesArray([