diff --git a/composer.json b/composer.json
index 5f62d889..7e1e6808 100644
--- a/composer.json
+++ b/composer.json
@@ -21,5 +21,11 @@
         "exclude-from-classmap": [
             "/library/HTMLPurifier/Language/"
         ]
+    },
+    "suggest": {
+        "cerdic/css-tidy": "If you want to use the filter 'Filter.ExtractStyleBlocks'.",
+        "ext-iconv": "Converts text to and from non-UTF-8 encodings",
+        "ext-bcmath": "Used for unit conversion and imagecrash protection",
+        "ext-tidy": "Used for pretty-printing HTML"
     }
 }