diff --git a/bootstrap.sh b/bootstrap.sh
old mode 100644
new mode 100755
index 800c8146..b993780f
--- a/bootstrap.sh
+++ b/bootstrap.sh
@@ -72,6 +72,7 @@ rm $kindlegen_tarball
 install 'MuPDF' mupdf mupdf-tools
 install 'FFmpeg' ffmpeg
 install 'Poppler' poppler-utils
+install 'Libffi' libffi-dev
 
 # Needed for docs generation.
 update-locale LANG=en_US.UTF-8 LANGUAGE=en_US.UTF-8 LC_ALL=en_US.UTF-8