diff --git a/CHANGES.md b/CHANGES.md
index c2d04162ecdd..599c90932dfb 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -8,6 +8,7 @@ Change Log
 * Fixed bug where if polylines were set to follow the surface of an undefined globe, Cesium would crash [#5413] https://github.com/AnalyticalGraphicsInc/cesium/pull/5413
 * Fixed a bug where picking clusters would return undefined instead of a list of the clustered entities. [#5286](https://github.com/AnalyticalGraphicsInc/cesium/issues/5286)
 * Reduced the amount of Sun bloom post-process effect near the horizon. [#5381](https://github.com/AnalyticalGraphicsInc/cesium/issues/5381)
+* Fixed a bug where camera zooming worked incorrectly when the display height was greater than the display width [#5421] (https://github.com/AnalyticalGraphicsInc/cesium/pull/5421)
 * Added Sandcastle demo for ArcticDEM data. [#5224](https://github.com/AnalyticalGraphicsInc/cesium/issues/5224)
 * `CzmlDataSource` and `KmlDataSource` load functions now take an optional `query` object, which will append query parameters to all network requests. [#5419](https://github.com/AnalyticalGraphicsInc/cesium/pull/5419), [#5434](https://github.com/AnalyticalGraphicsInc/cesium/pull/5434)
 * Fixed geocoder bug so geocoder can accurately handle NSEW inputs [#5407] (https://github.com/AnalyticalGraphicsInc/cesium/pull/5407)
diff --git a/Source/Scene/Camera.js b/Source/Scene/Camera.js
index d41ce2619e2e..029b8dfc6ad7 100644
--- a/Source/Scene/Camera.js
+++ b/Source/Scene/Camera.js
@@ -1820,30 +1820,57 @@ define([
         }
         //>>includeEnd('debug');
 
+        var ratio;
         amount = amount * 0.5;
-        var newRight = frustum.right - amount;
-        var newLeft = frustum.left + amount;
 
-        var maxRight = camera._maxCoord.x;
-        if (camera._scene.mapMode2D === MapMode2D.ROTATE) {
-            maxRight *= camera.maximumZoomFactor;
-        }
+        if((Math.abs(frustum.top) + Math.abs(frustum.bottom)) > (Math.abs(frustum.left) + Math.abs(frustum.right))) {
+            var newTop = frustum.top - amount;
+            var newBottom = frustum.bottom + amount;
 
-        if (newRight > maxRight) {
-            newRight = maxRight;
-            newLeft = -maxRight;
-        }
+            var maxBottom = camera._maxCoord.y;
+            if (camera._scene.mapMode2D === MapMode2D.ROTATE) {
+                maxBottom *= camera.maximumZoomFactor;
+            }
 
-        if (newRight <= newLeft) {
-            newRight = 1.0;
-            newLeft = -1.0;
-        }
+            if (newBottom > maxBottom) {
+                newBottom = maxBottom;
+                newTop = -maxBottom;
+            }
+
+            if (newTop <= newBottom) {
+                newTop = 1.0;
+                newBottom = -1.0;
+            }
+
+            ratio = frustum.right / frustum.top;
+            frustum.top = newTop;
+            frustum.bottom = newBottom;
+            frustum.right = frustum.top * ratio;
+            frustum.left = -frustum.right;
+        } else {
+            var newRight = frustum.right - amount;
+            var newLeft = frustum.left + amount;
 
-        var ratio = frustum.top / frustum.right;
-        frustum.right = newRight;
-        frustum.left = newLeft;
-        frustum.top = frustum.right * ratio;
-        frustum.bottom = -frustum.top;
+            var maxRight = camera._maxCoord.x;
+            if (camera._scene.mapMode2D === MapMode2D.ROTATE) {
+                maxRight *= camera.maximumZoomFactor;
+            }
+
+            if (newRight > maxRight) {
+                newRight = maxRight;
+                newLeft = -maxRight;
+            }
+
+            if (newRight <= newLeft) {
+                newRight = 1.0;
+                newLeft = -1.0;
+            }
+            ratio = frustum.top / frustum.right;
+            frustum.right = newRight;
+            frustum.left = newLeft;
+            frustum.top = frustum.right * ratio;
+            frustum.bottom = -frustum.top;
+        }
     }
 
     function zoom3D(camera, amount) {
diff --git a/Specs/Scene/CameraSpec.js b/Specs/Scene/CameraSpec.js
index ca983e47c813..63e083a0e037 100644
--- a/Specs/Scene/CameraSpec.js
+++ b/Specs/Scene/CameraSpec.js
@@ -1223,6 +1223,25 @@ defineSuite([
         expect(camera.frustum.bottom).toEqual(-1.25, CesiumMath.EPSILON10);
     });
 
+    it('zooms out 2D when frustrum has greater height than width', function() {
+        var frustum = new OrthographicOffCenterFrustum();
+        frustum.near = 1.0;
+        frustum.far = 2.0;
+        frustum.left = -1.0;
+        frustum.right = 1.0;
+        frustum.top = 2.0;
+        frustum.bottom = -2.0;
+        camera.frustum = frustum;
+
+        camera.update(SceneMode.SCENE2D);
+
+        camera.zoomOut(zoomAmount);
+        expect(camera.frustum.right).toEqualEpsilon(1.25, CesiumMath.EPSILON10);
+        expect(camera.frustum.left).toEqual(-1.25, CesiumMath.EPSILON10);
+        expect(camera.frustum.top).toEqual(2.5, CesiumMath.EPSILON10);
+        expect(camera.frustum.bottom).toEqual(-2.5, CesiumMath.EPSILON10);
+    });
+
     it('zooms in 2D', function() {
         var frustum = new OrthographicOffCenterFrustum();
         frustum.near = 1.0;
@@ -1242,6 +1261,25 @@ defineSuite([
         expect(camera.frustum.bottom).toEqual(-0.75, CesiumMath.EPSILON10);
     });
 
+    it('zooms in 2D when frustrum has greater height than width', function() {
+        var frustum = new OrthographicOffCenterFrustum();
+        frustum.near = 1.0;
+        frustum.far = 2.0;
+        frustum.left = -1.0;
+        frustum.right = 1.0;
+        frustum.top = 2.0;
+        frustum.bottom = -2.0;
+        camera.frustum = frustum;
+
+        camera.update(SceneMode.SCENE2D);
+
+        camera.zoomIn(zoomAmount);
+        expect(camera.frustum.right).toEqualEpsilon(0.75, CesiumMath.EPSILON10);
+        expect(camera.frustum.left).toEqual(-0.75, CesiumMath.EPSILON10);
+        expect(camera.frustum.top).toEqual(1.5, CesiumMath.EPSILON10);
+        expect(camera.frustum.bottom).toEqual(-1.5, CesiumMath.EPSILON10);
+    });
+
     it('clamps zoom out in 2D', function() {
         var frustum = new OrthographicOffCenterFrustum();
         frustum.near = 1.0;