diff --git a/demo/demo.component.ts b/demo/demo.component.ts
index e576f90..a777208 100644
--- a/demo/demo.component.ts
+++ b/demo/demo.component.ts
@@ -29,7 +29,7 @@ export class DemoComponent {
   public form: FormGroup;
   public value: number;
   public ngxCurrencyOptions = {
-    prefix: '',
+    prefix: 'R$ ',
     thousands: '.',
     decimal: ',',
     allowNegative: false,
diff --git a/package.json b/package.json
index 0c20b5c..978dc95 100644
--- a/package.json
+++ b/package.json
@@ -89,7 +89,7 @@
     "mocha": "3.3.0",
     "nyc": "^11.0.3",
     "rxjs": "5.0.1",
-    "sinon": "2.0.0",
+    "sinon": "^6.2.0",
     "sinon-chai": "2.8.0",
     "standard-version": "4.0.0",
     "ts-loader": "2.1.0",
diff --git a/src/input.service.ts b/src/input.service.ts
index 591aab4..bdb3fb3 100644
--- a/src/input.service.ts
+++ b/src/input.service.ts
@@ -3,7 +3,7 @@ import { CurrencyMaskConfig } from "./currency-mask.config";
 
 export class InputService {
 
-  private inputManager: InputManager;
+  inputManager: InputManager;
 
   constructor(private htmlInputElement: any, private options: CurrencyMaskConfig) {
     this.inputManager = new InputManager(htmlInputElement);
@@ -91,7 +91,7 @@ export class InputService {
     }
 
     let move = this.rawValue.substr(selectionStart - 1, 1).match(/\d/) ? 0 : -1;
-    move = (
+    if (
       (
         keyCode == 8 &&
         selectionStart - 1 === 0 &&
@@ -102,7 +102,9 @@ export class InputService {
         selectionStart === 0 &&
         !(this.rawValue.substr(selectionStart + 1, 1).match(/\d/))
       )
-    ) ? 1 : move;
+    ) {
+      move = 1;
+    };
     selectionEnd = keyCode == 46 || keyCode == 63272 ? selectionEnd + 1 : selectionEnd;
     selectionStart = keyCode == 8 ? selectionStart - 1 : selectionStart;
     this.rawValue = this.rawValue.substring(0, selectionStart) + this.rawValue.substring(selectionEnd, this.rawValue.length);
diff --git a/test/input-service.spec.ts b/test/input-service.spec.ts
new file mode 100644
index 0000000..8427386
--- /dev/null
+++ b/test/input-service.spec.ts
@@ -0,0 +1,58 @@
+import { InputService } from './../src/input.service';
+import { fakeAsync } from "@angular/core/testing";
+import { expect } from "chai";
+import { stub } from 'sinon';
+import {CurrencyMaskConfig} from "../src/currency-mask.config";
+
+describe('Testing InputService', () => {
+  var options: CurrencyMaskConfig = {
+    prefix: '',
+    suffix: '',
+    thousands: '.',
+    decimal: ',',
+    allowNegative: false,
+    nullable: false,
+    align: 'right',
+    allowZero: true,
+    precision: undefined,
+  };
+  var inputService: InputService;
+
+  describe('removeNumber', () => {
+    it('should call updateFieldValue with 1 when deleting the first number followed by a .', () => {
+      inputService = new InputService({
+        selectionStart: 0,
+        selectionEnd: 0,
+      }, options);
+
+      inputService.inputManager.rawValue = '1.234,50';
+      inputService.updateFieldValue = stub();
+      inputService.removeNumber(46);
+      expect(inputService.updateFieldValue).to.be.calledWith(1);
+    });
+
+    it('should call updateFieldValue with 1 when backspacing the first number followed by a .', () => {
+      inputService = new InputService({
+        selectionStart: 1,
+        selectionEnd: 1,
+      }, options);
+
+      inputService.inputManager.rawValue = '1.234,50';
+      inputService.updateFieldValue = stub();
+      inputService.removeNumber(8);
+      expect(inputService.updateFieldValue).to.be.calledWith(1);
+    });
+
+    it('should call updateFieldValue with 2 less than the current position when backspacing any non-number character', () => {
+      inputService = new InputService({
+        selectionStart: 6,
+        selectionEnd: 6,
+      }, options);
+
+      inputService.inputManager.rawValue = '1.234,50';
+      inputService.updateFieldValue = stub();
+      inputService.removeNumber(8);
+      expect(inputService.updateFieldValue).to.be.calledWith(4);
+    });
+  });
+});