diff --git a/Gemfile b/Gemfile
index be173b2..49aee2f 100644
--- a/Gemfile
+++ b/Gemfile
@@ -3,3 +3,6 @@
 source "https://rubygems.org"
 
 gemspec
+
+# FIXME: remove this after drop support for Ruby 2.7
+gem "ffi", "< 1.17"