diff --git a/README.md b/README.md
index 7d01128..f07a0f0 100644
--- a/README.md
+++ b/README.md
@@ -1,7 +1,7 @@
 # Trimage image compressor
 A cross-platform tool for optimizing PNG and JPG files.
 
-Trimage is a cross-platform GUI and command-line interface to optimize image files via [optipng](http://optipng.sourceforge.net), [advpng](http://advancemame.sourceforge.net/comp-readme.html) and [jpegoptim](http://www.kokkonen.net/tjko/projects.html), depending on the
+Trimage is a cross-platform GUI and command-line interface to optimize image files via [advpng](http://advancemame.sourceforge.net/comp-readme.html), [jpegoptim](http://www.kokkonen.net/tjko/projects.html), [optipng](http://optipng.sourceforge.net) and [pngcrush](https://pmt.sourceforge.io/pngcrush) depending on the
 filetype (currently, PNG and JPG files are supported).
 It was inspired by
 [imageoptim](http://imageoptim.pornel.net).
@@ -12,3 +12,10 @@ various input functions to fit your own workflow: a regular file dialog,
 dragging and dropping and various command line options.
 
 Visit [Trimage.org](http://trimage.org) for more information.
+
+## Prerequisites
+
+- advpng
+- jpegoptim
+- optipng
+- pngcrush