diff --git a/lib/QRCode.js b/lib/QRCode.js
index 7471f47..d0bc10c 100644
--- a/lib/QRCode.js
+++ b/lib/QRCode.js
@@ -20,14 +20,14 @@ function renderCanvas(canvas) {
     if(window.innerHeight > size) canvas.style.top = (window.innerHeight - size) / 2 + 'px';
     ctx.fillRect(0, 0, size, size);
     var cells = this.cells;
-    var cellWidth = this.size / cells.length;
-    var cellHeight = this.size / cells.length;
+    var cellWidth = (this.size - 1)/ cells.length;
+    var cellHeight = (this.size - 1)/ cells.length;
     var nRoundedWidth = Math.round(cellWidth);
     var nRoundedHeight = Math.round(cellHeight);
     cells.forEach(function(row, rowIndex) {
         row.forEach(function(column, columnIndex) {
-            var nLeft = columnIndex * cellWidth;
-            var nTop = rowIndex * cellHeight;
+            var nLeft = columnIndex * cellWidth + 1;
+            var nTop = rowIndex * cellHeight + 1;
             ctx.fillStyle = ctx.strokeStyle = column ? bgColor : fgColor;
             ctx.lineWidth = 1;
             ctx.fillRect(nLeft, nTop, cellWidth, cellHeight);