diff --git a/jquery.flot.stack.js b/jquery.flot.stack.js
index 6d8105d..ace7011 100644
--- a/jquery.flot.stack.js
+++ b/jquery.flot.stack.js
@@ -71,7 +71,7 @@ adjusted (e.g for bar charts or filled areas).
                 fromgap = true,
                 keyOffset = horizontal ? 1 : 0,
                 accumulateOffset = horizontal ? 0 : 1,
-                i = 0, j = 0, l;
+                i = 0, j = 0, l, m;
 
             while (true) {
                 if (i >= points.length)