1 files changed, 1 insertions, 1 deletions

diff --git a/js/RrdGraph.js b/js/RrdGraph.js
index 6bd75c9..e43fa51 100644
--- a/js/RrdGraph.js
+++ b/js/RrdGraph.js
@@ -323,7 +323,7 @@ RrdGraphDesc.prototype.gprint = function (graph, vname, cf, format, strftimefmt)
         this.vname = vname;
         this.vidx = graph.find_var(vname);
         this.legend = '';
-        if (format === undefined) {
+        if (!format) {
                 this.format = cf;
                 switch (graph.gdes[this.vidx].gf) {
                         case RrdGraphDesc.GF_DEF: