diff --git a/README.md b/README.md
index 50e4670..4879b03 100644
--- a/README.md
+++ b/README.md
@@ -17,9 +17,9 @@ npm install microstats
 const microstats = require('microstats')
 
 // Event emits
-microstats.on('memory', function(value) { console.log('MEMORY:', memory }
-microstats.on('cpu', function(value) { console.log('CPU:', memory }
-microstats.on('disk', function(value) { console.log('DISK:', memory }
+microstats.on('memory', function(value) { console.log('MEMORY:', value) })
+microstats.on('cpu', function(value) { console.log('CPU:', value) })
+microstats.on('disk', function(value) { console.log('DISK:', value) })
 
 let options = {}
 microstats.start(options, function(err) {
diff --git a/optionsparser.js b/optionsparser.js
index b1672ae..50b9301 100644
--- a/optionsparser.js
+++ b/optionsparser.js
@@ -4,6 +4,8 @@ const util = require('util');
 // frequency: '2s'
 exports.getFrequency = function(options) {
     let f = {}; 
+    let g = null;
+    let regexp = /^(\d+)([smh])$/;
     
     if(!options || !options.frequency) {
         f.mode = 'once';
@@ -20,13 +22,14 @@ exports.getFrequency = function(options) {
         f.interval = 2000; // check for alert condition every 2 seconds
         return f;
     }
-    else if(options.frequency.length !== 2 || isNaN(options.frequency[0])) {
+    else if(regexp.test(options.frequency)) {
+        g = regexp.exec(options.frequency);
+    } else
         throw "Invalid frequency. Try something like 'once', 'onalert', '2m' or '1h'";   
-    }
     
     f.mode = 'time';
-    let n = parseInt(options.frequency[0]);
-    let s = options.frequency[1];
+    let n = parseInt(g[1]);
+    let s = g[2];
         
     switch(s) {
         case 's': f.interval = n * 1000; break;
@@ -91,4 +94,4 @@ exports.getDiskUsedAlertThreshold = function(diskoptions) {
     }
     
     return parseInt(u.split('>')[1].split('%')[0]);    
-}
\ No newline at end of file
+}