diff --git a/src/scripts/charts/bar.js b/src/scripts/charts/bar.js
index cf13232..75595d6 100644
--- a/src/scripts/charts/bar.js
+++ b/src/scripts/charts/bar.js
@@ -352,7 +352,7 @@
 
         // Create bar element
         bar = seriesElement.elem('line', positions, options.classNames.bar).attr({
-          'ct:value': [value.x, value.y].filter(Chartist.isNum).join(','),
+          'ct:value': [value.x, value.y].filter(Chartist.isNumeric).join(','),
           'ct:meta': Chartist.getMetaData(series, valueIndex)
         });
 
diff --git a/src/scripts/charts/line.js b/src/scripts/charts/line.js
index 862d2ef..d014aea 100644
--- a/src/scripts/charts/line.js
+++ b/src/scripts/charts/line.js
@@ -141,8 +141,8 @@
 
     if(options.axisY.type === undefined) {
       axisY = new Chartist.AutoScaleAxis(Chartist.Axis.units.y, data, chartRect, Chartist.extend({}, options.axisY, {
-        high: Chartist.isNum(options.high) ? options.high : options.axisY.high,
-        low: Chartist.isNum(options.low) ? options.low : options.axisY.low
+        high: Chartist.isNumeric(options.high) ? options.high : options.axisY.high,
+        low: Chartist.isNumeric(options.low) ? options.low : options.axisY.low
       }));
     } else {
       axisY = options.axisY.type.call(Chartist, Chartist.Axis.units.y, data, chartRect, options.axisY);
@@ -213,7 +213,7 @@
             x2: pathElement.x + 0.01,
             y2: pathElement.y
           }, options.classNames.point).attr({
-            'ct:value': [pathElement.data.value.x, pathElement.data.value.y].filter(Chartist.isNum).join(','),
+            'ct:value': [pathElement.data.value.x, pathElement.data.value.y].filter(Chartist.isNumeric).join(','),
             'ct:meta': pathElement.data.meta
           });
 
diff --git a/src/scripts/core.js b/src/scripts/core.js
index 3054d7e..e7534a7 100644
--- a/src/scripts/core.js
+++ b/src/scripts/core.js
@@ -579,14 +579,14 @@ var Chartist = {
   };
 
   /**
-   * Checks if the value is a valid number or string with a number.
+   * Checks if a value can be safely coerced to a number. This includes all values except null which result in finite numbers when coerced. This excludes NaN, since it's not finite.
    *
    * @memberof Chartist.Core
    * @param value
    * @returns {Boolean}
    */
-  Chartist.isNum = function(value) {
-    return (typeof value === "number" || typeof value === "string") && !isNaN(value) && isFinite(value);
+  Chartist.isNumeric = function(value) {
+    return value === null ? false : isFinite(value);
   };
 
   /**
@@ -608,7 +608,7 @@ var Chartist = {
    * @returns {*}
    */
   Chartist.getNumberOrUndefined = function(value) {
-    return Chartist.isNum(value) ? +value : undefined;
+    return Chartist.isNumeric(value) ? +value : undefined;
   };
 
   /**
@@ -620,7 +620,7 @@ var Chartist = {
    * @returns {*}
    */
   Chartist.getMultiValue = function(value, dimension, defaultValue) {
-    if(Chartist.isNum(value)) {
+    if(Chartist.isNumeric(value)) {
       return +value;
     } else if(value) {
       return Chartist.isFalseyButZero(value[dimension || 'y']) ? defaultValue : value[dimension || 'y'];