diff --git a/src/components/About/About.js b/src/components/About/About.js
index 2a57779..8d0e57e 100644
--- a/src/components/About/About.js
+++ b/src/components/About/About.js
@@ -44,10 +44,4 @@ About.propTypes = {
   title: PropTypes.string,
   pageTitle: PropTypes.string,
   email: PropTypes.string
-}
-
-About.defaultProps = {
-  title: null,
-  pageTitle: null,
-  email: null
 }
\ No newline at end of file
diff --git a/src/components/Articles/Categories/Categories.js b/src/components/Articles/Categories/Categories.js
index 0968a8a..eeb0446 100644
--- a/src/components/Articles/Categories/Categories.js
+++ b/src/components/Articles/Categories/Categories.js
@@ -1,4 +1,5 @@
 import React from 'react';
+import PropTypes from 'prop-types'
 import { useLocation } from '@reach/router'
 import { Link } from 'gatsby'
 
@@ -18,4 +19,8 @@ const Categories = ({ children, setQuery = () => null }) => {
   )
 }
 
-export default Categories
\ No newline at end of file
+export default Categories
+
+Categories.propTypes = {
+  setQuery: PropTypes.func
+}
\ No newline at end of file
diff --git a/src/components/Articles/Search/Search.js b/src/components/Articles/Search/Search.js
index 921fc04..40f4b8c 100644
--- a/src/components/Articles/Search/Search.js
+++ b/src/components/Articles/Search/Search.js
@@ -28,5 +28,13 @@ const Search = ({ allArticles, filterArticles, articlesLength, resultsLength, qu
 export default Search
 
 Search.propTypes = {
-	articlesLength: PropTypes.number
+	allArticles: PropTypes.array,
+	filterArticles: PropTypes.func,
+	articlesLength: PropTypes.number,
+	resultsLength: PropTypes.number,
+	query: PropTypes.string,
+	setQuery: PropTypes.func,
+	setFiltredArticles: PropTypes.func,
+	setLimit: PropTypes.func,
+	onPage: PropTypes.number
 }
\ No newline at end of file
diff --git a/src/components/SEO/SEO.js b/src/components/SEO/SEO.js
index bce35cc..9598530 100644
--- a/src/components/SEO/SEO.js
+++ b/src/components/SEO/SEO.js
@@ -70,11 +70,11 @@ export default SEO
 
 SEO.propTypes = {
   title: PropTypes.string,
-  description: PropTypes.string
-}
-
-SEO.defaultProps = {
-  title: null,
-  description: null
+  titleTemplate: PropTypes.bool,
+  keywords: PropTypes.string,
+  description: PropTypes.string,
+  image: PropTypes.string,
+  type: PropTypes.string,
+  canonical: PropTypes.string
 }
 
diff --git a/src/components/ViewCounter/ViewCounter.js b/src/components/ViewCounter/ViewCounter.js
index 1104f6a..6405cd3 100644
--- a/src/components/ViewCounter/ViewCounter.js
+++ b/src/components/ViewCounter/ViewCounter.js
@@ -1,4 +1,5 @@
 import React, { useEffect, useState } from 'react';
+import PropTypes from 'prop-types'
 import firebase from 'gatsby-plugin-firebase';
 import incrementViews from '../../lib/increment-views';
 
@@ -28,4 +29,8 @@ const ViewCounter = ({ id }) => {
   );
 };
 
-export default ViewCounter;
\ No newline at end of file
+export default ViewCounter;
+
+ViewCounter.propTypes = {
+  id: PropTypes.string
+}
\ No newline at end of file