diff --git a/README.md b/README.md
index 9fe47f6ad..0b94c0d0c 100644
--- a/README.md
+++ b/README.md
@@ -37,6 +37,8 @@ bundle exec bin/rails s
 ```
 
 Para ejecutar los tests:
+
+Prerequisitos: tener instalado PhantomJS >= 2.0 
 ```
 bundle exec bin/rspec
 ```
diff --git a/README_EN.md b/README_EN.md
index 40a39ae01..bb925b288 100644
--- a/README_EN.md
+++ b/README_EN.md
@@ -38,6 +38,8 @@ bundle exec bin/rails s
 ```
 
 Run the tests with:
+
+Prerequisites: install PhantomJS >= 2.0
 ```
 bundle exec bin/rspec
 ```