diff --git a/src/svg.js b/src/svg.js
index 626bfcf..faec271 100644
--- a/src/svg.js
+++ b/src/svg.js
@@ -71,7 +71,6 @@ var has = "hasOwnProperty",
     objectToString = Object.prototype.toString,
     ISURL = /^url\(['"]?([^\)]+?)['"]?\)$/i,
     colourRegExp = /^\s*((#[a-f\d]{6})|(#[a-f\d]{3})|rgba?\(\s*([\d\.]+%?\s*,\s*[\d\.]+%?\s*,\s*[\d\.]+%?(?:\s*,\s*[\d\.]+%?)?)\s*\)|hsba?\(\s*([\d\.]+(?:deg|\xb0|%)?\s*,\s*[\d\.]+%?\s*,\s*[\d\.]+(?:%?\s*,\s*[\d\.]+)?%?)\s*\)|hsla?\(\s*([\d\.]+(?:deg|\xb0|%)?\s*,\s*[\d\.]+%?\s*,\s*[\d\.]+(?:%?\s*,\s*[\d\.]+)?%?)\s*\))\s*$/i,
-    isnan = {"NaN": 1, "Infinity": 1, "-Infinity": 1},
     bezierrg = /^(?:cubic-)?bezier\(([^,]+),([^,]+),([^,]+),([^\)]+)\)/,
     reURLValue = /^url\(#?([^)]+)\)$/,
     spaces = "\x09\x0a\x0b\x0c\x0d\x20\xa0\u1680\u180e\u2000\u2001\u2002\u2003\u2004\u2005\u2006\u2007\u2008\u2009\u200a\u202f\u205f\u3000\u2028\u2029",
@@ -139,7 +138,7 @@ function getAttrs(el) {
 function is(o, type) {
     type = Str.prototype.toLowerCase.call(type);
     if (type == "finite") {
-        return !isnan[has](+o);
+        return isFinite(o);
     }
     if (type == "array" &&
         (o instanceof Array || Array.isArray && Array.isArray(o))) {