diff --git a/src/components/Converter.jsx b/src/components/Converter.jsx
index be61a8b..2323af4 100644
--- a/src/components/Converter.jsx
+++ b/src/components/Converter.jsx
@@ -12,7 +12,7 @@ import ArrowDown from './svg/ArrowDown'
 import Cancel from './svg/Cancel'
 
 import { convert } from '../api'
-import { removeByKey, uniqueFiles, displayOutputFileName, filterImages } from '../helpers/util'
+import { removeByKey, uniqueAndValidFiles, displayOutputFileName, filterImages } from '../helpers/util'
 import {
   fileTypes,
   MERGE,
@@ -26,10 +26,10 @@ import {
 
 const drop = (props, monitor, component) => {
   const { files } = monitor.getItem()
-  const filesUnique = uniqueFiles(component.state.files, files)
+  const stagingFiles = uniqueAndValidFiles(component.state.files, files)
   component.setState({
-    status: Object.keys(filesUnique).length ? STAGING : IDLE,
-    files: filesUnique
+    status: Object.keys(stagingFiles).length ? STAGING : IDLE,
+    files: stagingFiles
   })
 
   if (component.state.shifted) {
diff --git a/src/helpers/util.js b/src/helpers/util.js
index 0b4cd33..339edb2 100644
--- a/src/helpers/util.js
+++ b/src/helpers/util.js
@@ -1,4 +1,5 @@
 const { pluck, compose, map } = require('./functional')
+const { fileTypes } = require('./constants')
 
 const replaceSpaceCharacters = str =>
   str.replace(/\s/g, '\\ ')
@@ -26,9 +27,15 @@ function centerEllipsis(str, length = 7) {
 const displayOutputFileName = outputType =>
   compose(filterImages, map(pluck('path')), createOutputFileName(outputType), centerEllipsis)
 
-const uniqueFiles = (files, newArray) =>
+const fileTypesArr = [].concat(...(Object.keys(fileTypes).map(key => fileTypes[key])))
+
+const isValidFileType = fileType => fileTypesArr.indexOf(fileType) > -1
+
+const getFileType = fileName => fileName.split('.').pop()
+
+const uniqueAndValidFiles = (files, newArray) =>
   newArray.reduce((accum, next) => {
-    if (accum[next.path]) return accum
+    if (accum[next.path] || !isValidFileType(getFileType(next.name))) return accum
     return Object.assign(accum, {
       [next.path]: next
     })
@@ -48,5 +55,5 @@ module.exports = {
   concatFiles,
   removeByKey,
   replaceSpaceCharacters,
-  uniqueFiles
+  uniqueAndValidFiles,
 }