diff --git a/src/App.js b/src/App.js
index 8ddc45d..92e693d 100644
--- a/src/App.js
+++ b/src/App.js
@@ -23,8 +23,8 @@ const Sidebar = (props) => {
     if (pix === undefined) { return <p key={md.name}>Loading...</p>; }
     let max = binaryMax[md.name];
     let [w, h] = md.size;
-    let xOff = mouseX; // Math.min(w, Math.max(0, Math.round(x*w)));
-    let yOff = mouseY; // Math.min(h, Math.max(0, Math.round(y*h)));
+    let xOff = Math.min(mouseX,w-1); // Math.min(w, Math.max(0, Math.round(x*w)));
+    let yOff = Math.min(mouseY,h-1); // Math.min(h, Math.max(0, Math.round(y*h)));
     let v = pix[xOff+yOff*w];
     let color = "#fff";
     let rgb = "";