diff --git a/src/tools/brush-selection.ts b/src/tools/brush-selection.ts
index 71c5ad9..95b2c3e 100644
--- a/src/tools/brush-selection.ts
+++ b/src/tools/brush-selection.ts
@@ -24,6 +24,7 @@ class BrushSelection {
 
         const prev = { x: 0, y: 0 };
         let dragId: number | undefined;
+        let wheelModeBrushSize = false;
 
         const update = (e: PointerEvent) => {
             const x = e.offsetX;
@@ -104,12 +105,37 @@ class BrushSelection {
             }
         };
 
+        const wheel = (e: WheelEvent) => {
+            if(wheelModeBrushSize){
+                if(e.deltaY > 0)
+                    radius = Math.max(1, radius * 1.05);            
+                else
+                    radius = Math.max(1, radius / 1.05);
+                circle.setAttribute('r', radius.toString());
+                e.preventDefault();
+                e.stopPropagation();
+            }
+        };
+
+        const keydown = (e: KeyboardEvent) => {
+            if (e.shiftKey) {
+                wheelModeBrushSize = true;
+            }
+        };
+          
+        const keyup = (e: KeyboardEvent) => {
+            wheelModeBrushSize = false;
+        };
+
         this.activate = () => {
             svg.style.display = 'inline';
             parent.style.display = 'block';
             parent.addEventListener('pointerdown', pointerdown);
             parent.addEventListener('pointermove', pointermove);
             parent.addEventListener('pointerup', pointerup);
+            parent.addEventListener('wheel', wheel);
+            document.addEventListener('keydown', keydown);
+            document.addEventListener('keyup', keyup);
         };
 
         this.deactivate = () => {
@@ -122,6 +148,10 @@ class BrushSelection {
             parent.removeEventListener('pointerdown', pointerdown);
             parent.removeEventListener('pointermove', pointermove);
             parent.removeEventListener('pointerup', pointerup);
+            parent.removeEventListener('wheel', wheel);
+            document.removeEventListener('keydown', keydown);
+            document.removeEventListener('keyup', keyup); 
+            wheelModeBrushSize = false;
         };
 
         events.on('tool.brushSelection.smaller', () => {