diff --git a/lib/index.js b/lib/index.js
index 43e3149e..c2764b46 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -48,9 +48,18 @@ export default class PhoneInput extends Component {
     updateFlagAndFormatNumber(number, actionAfterSetState = null){
         var iso2 = this.props.initialCountry || 'us'
         var phoneNumber = number
+        var numberPattern = new RegExp('^[\+0-9-]+$');
         if(number){
             if(phoneNumber[0] != '+')
                 phoneNumber = `+${phoneNumber}`
+
+             while(!numberPattern.test(phoneNumber))
+                phoneNumber = phoneNumber.slice(0, phoneNumber.length - 1);
+            
+            if(phoneNumber.length > 20)
+                while(phoneNumber.length > 20)
+                    phoneNumber = phoneNumber.slice(0, phoneNumber.length - 1);
+
             iso2 = PhoneNumber.getCountryCodeOfNumber(phoneNumber)
         }
         this.setState({iso2, formattedNumber: phoneNumber}, actionAfterSetState)