diff --git a/src/kiss_flixel/CameraTools.hx b/src/kiss_flixel/CameraTools.hx
index b7c140f..0f7221e 100644
--- a/src/kiss_flixel/CameraTools.hx
+++ b/src/kiss_flixel/CameraTools.hx
@@ -7,6 +7,7 @@ import flash.display.BitmapData;
 import flixel.FlxCamera;
 import flixel.math.FlxVector;
 import flixel.math.FlxPoint;
+import flixel.math.FlxRect;
 import flixel.FlxSprite;
 import flixel.FlxG;
 import flixel.util.FlxColor;
diff --git a/src/kiss_flixel/CameraTools.kiss b/src/kiss_flixel/CameraTools.kiss
index aa03588..6673d4e 100644
--- a/src/kiss_flixel/CameraTools.kiss
+++ b/src/kiss_flixel/CameraTools.kiss
@@ -76,20 +76,36 @@
                     (<= (- bottom margin) mPos.y)
                 (<= (- bottom margin) mPos.y bottom)))))
 
-(function updateScrollWheelZoom [:FlxCamera camera :Float elapsed :Float speed]
-    #{
-        if (FlxG.mouse.wheel != 0) {
-            camera.zoom += (FlxG.mouse.wheel * elapsed * speed);
-        }
-    }#)
+// GOTCHA: if you change FlxG.camera to a moving camera, you MUST provide a default camera for FlxG.mouse.getScreenPosition()
+(function updateScrollWheelZoom [:FlxCamera camera :Float elapsed :Float speed &opt :FlxCamera screenCamera]
+    (case FlxG.mouse.wheel
+        (0 null)
+        (v
+            (let [deltaZoom (* camera.zoom v elapsed speed)
+                    scrollPosition (camera.scroll.copyTo)
+                    mouseWorldPosition (FlxG.mouse.getWorldPosition camera)]
+                (+= camera.zoom deltaZoom)
+                (let [newMouseWorldPosition (FlxG.mouse.getWorldPosition camera)
+                        deltaMousePosition (newMouseWorldPosition.subtractPoint mouseWorldPosition)]
+                    (camera.scroll.subtractPoint deltaMousePosition))
+                    // Undo any scrolling that expands the viewport past its bounds
+                    **(unless (.containsPoint (getScrollBounds camera) camera.scroll)
+                        (-= camera.zoom deltaZoom)
+                        (set camera.scroll scrollPosition))))
+        (otherwise null)))
 
-(function calculateScrollBounds <>[:FlxObject T] [:FlxCamera camera :FlxTypedGroup<T> group &opt :Float margin]
-    (let [r (GroupTools.calculateBounds group margin)]
-        (camera.setScrollBoundsRect r.x r.y r.width r.height)))
+(function getScrollBounds [:FlxCamera camera]
+    (.fromTwoPoints (new FlxRect) (new FlxPoint camera.minScrollX camera.minScrollY) (new FlxPoint camera.maxScrollX camera.maxScrollY)))
 
-(function extendScrollBounds [:FlxCamera camera :FlxObject object &opt :Float margin]
+// GOTCHA: if you change FlxG.camera to a moving camera, you MUST provide a default camera for FlxG.mouse.getScreenPosition()
+(function calculateScrollBounds <>[:FlxSprite T] [:FlxCamera camera :FlxTypedGroup<T> group &opt :FlxCamera screenCamera :Float margin]
+    (let [r (GroupTools.calculateScreenBounds group screenCamera margin)]
+        (camera.setScrollBoundsRect r.x r.y ~r.width ~r.height)))
+
+// GOTCHA: if you change FlxG.camera to a moving camera, you MUST provide a default camera for FlxG.mouse.getScreenPosition()
+(function extendScrollBounds [:FlxCamera camera :FlxSprite sprite &opt :FlxCamera screenCamera :Float margin]
     // if the given object is out of bounds, extend the bounds
-    (let [r (object.getRotatedBounds)]
+    (let [r (sprite.getScreenBounds camera)]
         (setMin camera.minScrollX (- r.left margin))
         (setMin camera.minScrollY (- r.top margin))
         (setMax camera.maxScrollX (+ r.right margin))
diff --git a/src/kiss_flixel/GroupTools.hx b/src/kiss_flixel/GroupTools.hx
index 91cfd69..a1f5ff4 100644
--- a/src/kiss_flixel/GroupTools.hx
+++ b/src/kiss_flixel/GroupTools.hx
@@ -6,7 +6,9 @@ import flixel.FlxObject;
 import flixel.FlxState;
 import flixel.math.FlxRect;
 import flixel.math.FlxPoint;
+import flixel.FlxCamera;
 import flixel.group.FlxGroup;
+import flixel.FlxSprite;
 
 @:build(kiss.Kiss.build())
 class GroupTools {}
diff --git a/src/kiss_flixel/GroupTools.kiss b/src/kiss_flixel/GroupTools.kiss
index 22be101..6726081 100644
--- a/src/kiss_flixel/GroupTools.kiss
+++ b/src/kiss_flixel/GroupTools.kiss
@@ -8,20 +8,22 @@
         (group.remove obj)
         (group.insert 0 obj)))
 
-(function :FlxRect calculateBounds <>[:FlxObject T] [:FlxTypedGroup<T> group &opt :Float margin]
+(function :FlxRect calculateScreenBounds <>[:FlxSprite T] [:FlxTypedGroup<T> group &opt :FlxCamera camera :Float margin]
     (unless margin (set margin 0))
-    (let [&mut minX 0
-            &mut maxX 0
-            &mut minY 0
-            &mut maxY 0
-            r (new FlxRect)]
+    (let [s (group.getFirstAlive)
+            r (new FlxRect)
+            bounds (s.getScreenBounds r camera)
+            &mut minX bounds.left
+            &mut maxX bounds.right
+            &mut minY bounds.top
+            &mut maxY bounds.bottom]
         
-        (group.forEach ->object
-            (let [bounds (object.getRotatedBounds r)]
-                (set minX (min minX bounds.left))
-                (set minY (min minY bounds.top))
-                (set maxX (max maxX bounds.right))
-                (set maxY (max maxY bounds.bottom))))
+        (group.forEach ->sprite
+            (let [bounds (sprite.getScreenBounds r camera)]
+                (setMin minX bounds.left)
+                (setMin minY bounds.top)
+                (setMax maxX bounds.right)
+                (setMax maxY bounds.bottom)))
 
         (r.fromTwoPoints
             (new FlxPoint (- minX margin) (- minY margin))