diff --git a/core/rfb.js b/core/rfb.js
index 0f33057d..8ac38aab 100644
--- a/core/rfb.js
+++ b/core/rfb.js
@@ -2486,13 +2486,11 @@ export default class RFB extends EventTargetMixin {
                 if (this._sock.rQwait("rect header", 12)) { return false; }
                 /* New FramebufferUpdate */
 
-                const hdr = this._sock.rQshiftBytes(12);
-                this._FBU.x        = (hdr[0] << 8) + hdr[1];
-                this._FBU.y        = (hdr[2] << 8) + hdr[3];
-                this._FBU.width    = (hdr[4] << 8) + hdr[5];
-                this._FBU.height   = (hdr[6] << 8) + hdr[7];
-                this._FBU.encoding = parseInt((hdr[8] << 24) + (hdr[9] << 16) +
-                                              (hdr[10] << 8) + hdr[11], 10);
+                this._FBU.x = this._sock.rQshift16();
+                this._FBU.y = this._sock.rQshift16();
+                this._FBU.width = this._sock.rQshift16();
+                this._FBU.height = this._sock.rQshift16();
+                this._FBU.encoding = this._sock.rQshift32();
             }
 
             if (!this._handleRect()) {