diff --git a/js/CanvasView.js b/js/CanvasView.js
index 45e5255..987aec9 100644
--- a/js/CanvasView.js
+++ b/js/CanvasView.js
@@ -1056,9 +1056,9 @@ async function handleSAMDetectorResult(node, resultImage) {
             });
             throw new Error("Mask tool not available or not initialized");
         }
-        log.debug("Applying SAM mask to canvas using setMask method");
-        // Use the setMask method which handles positioning automatically
-        canvas.maskTool.setMask(maskAsImage);
+        log.debug("Applying SAM mask to canvas using addMask method");
+        // Use the addMask method which overlays on existing mask without clearing it
+        canvas.maskTool.addMask(maskAsImage);
         // Update canvas and save state (same as CanvasMask)
         canvas.render();
         canvas.saveState();
diff --git a/js/MaskTool.js b/js/MaskTool.js
index 9bbfa56..250f7a3 100644
--- a/js/MaskTool.js
+++ b/js/MaskTool.js
@@ -258,4 +258,16 @@ export class MaskTool {
         this.canvasInstance.render();
         log.info(`MaskTool updated with a new mask image at correct canvas position (${destX}, ${destY}).`);
     }
+    addMask(image) {
+        const destX = -this.x;
+        const destY = -this.y;
+        // Don't clear existing mask - just add to it
+        this.maskCtx.globalCompositeOperation = 'source-over';
+        this.maskCtx.drawImage(image, destX, destY);
+        if (this.onStateChange) {
+            this.onStateChange();
+        }
+        this.canvasInstance.render();
+        log.info(`MaskTool added mask overlay at correct canvas position (${destX}, ${destY}) without clearing existing mask.`);
+    }
 }
diff --git a/src/CanvasView.ts b/src/CanvasView.ts
index 5594e0c..a7cdb41 100644
--- a/src/CanvasView.ts
+++ b/src/CanvasView.ts
@@ -1170,10 +1170,10 @@ async function handleSAMDetectorResult(node: ComfyNode, resultImage: HTMLImageEl
             throw new Error("Mask tool not available or not initialized");
         }
 
-        log.debug("Applying SAM mask to canvas using setMask method");
+        log.debug("Applying SAM mask to canvas using addMask method");
 
-        // Use the setMask method which handles positioning automatically
-        canvas.maskTool.setMask(maskAsImage);
+        // Use the addMask method which overlays on existing mask without clearing it
+        canvas.maskTool.addMask(maskAsImage);
 
         // Update canvas and save state (same as CanvasMask)
         canvas.render();
diff --git a/src/MaskTool.ts b/src/MaskTool.ts
index 0cf44db..d0b481c 100644
--- a/src/MaskTool.ts
+++ b/src/MaskTool.ts
@@ -336,4 +336,19 @@ export class MaskTool {
         this.canvasInstance.render();
         log.info(`MaskTool updated with a new mask image at correct canvas position (${destX}, ${destY}).`);
     }
+
+    addMask(image: HTMLImageElement): void {
+        const destX = -this.x;
+        const destY = -this.y;
+
+        // Don't clear existing mask - just add to it
+        this.maskCtx.globalCompositeOperation = 'source-over';
+        this.maskCtx.drawImage(image, destX, destY);
+
+        if (this.onStateChange) {
+            this.onStateChange();
+        }
+        this.canvasInstance.render();
+        log.info(`MaskTool added mask overlay at correct canvas position (${destX}, ${destY}) without clearing existing mask.`);
+    }
 }