diff --git a/composer.json b/composer.json
index f613dd5..86fb672 100644
--- a/composer.json
+++ b/composer.json
@@ -11,7 +11,7 @@
     "require": {
         "Christian-Riesen/base32": "^1.2",
         "psr/cache": "^1.0",
-        "paragonie/random_compat": "^2.0"
+        "paragonie/random_compat": "^2.0|~9.99"
     },
     "require-dev": {
         "phpunit/phpunit": "~6",