diff --git a/readme.md b/readme.md
index 88a91b4..25ec08b 100644
--- a/readme.md
+++ b/readme.md
@@ -36,6 +36,8 @@ to only print a report:
 - [`file`](https://darwinsys.com/file/) - to determine file type
 - [`sd`](https://github.com/chmln/sd) – better sed
 - [`jpegoptim`](https://github.com/tjko/jpegoptim) – to compress JPEGs
+- [`imagemagick`](https://imagemagick.org/)
+  or [`graphicsmagic`](http://www.graphicsmagick.org/) – to mogrify PNGs
 - [`pngcrush`](https://github.com/Kjuly/pngcrush) – to compress PNGs
 <!-- - [`pngquant`](https://github.com/kornelski/pngquant) – to compress PNGs -->
 
diff --git a/rename-ext.sh b/rename-ext.sh
index cfe04da..191596c 100755
--- a/rename-ext.sh
+++ b/rename-ext.sh
@@ -17,6 +17,7 @@
 # - file - to determine file type
 # - `cargo install sd` – better sed
 # - jpegoptim – to compress JPEGs
+# - imagemagick or graphicsmagic – to mogrify PNGs
 # - pngcrush – to compress PNGs (losless)
 # // - pngquant – to compress PNGs (lossy)
 
@@ -25,7 +26,7 @@ ALL_EXTS=`echo \
   |eps|tga|tiff?|psd|ico|xcf|heic
   |eot|otf|ttf|epub|doc|docx|xls|swf|pdf|odt
   |flac|opus|ogg|m4a|wav
-  |mpe?g|mp\d|mov|mkv|avif?|asf|3gpp?
+  |mpe?g|mp\d|mov|mkv|avif?|asf|3gpp?|av1
   |html?|sh|py|php
   ' \
   |  tr -d '[:space:]' \
@@ -232,6 +233,7 @@ for FILENAME in "$@"; do
   'image/jp2') rename_ext "$FILENAME" 'jp2' ;;
   'image/png') rename_ext "$FILENAME" 'png' ;;
   'image/webp') rename_ext "$FILENAME" 'webp' ;;
+  'image/avif') rename_ext "$FILENAME" 'avif' ;;
 
   # vector-based
   'image/svg+xml') rename_ext "$FILENAME" 'svg' ;;