diff --git a/requirements.txt b/requirements.txt
index e7c4849e8..0e3be6b1a 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -4,6 +4,7 @@ glyphsLib==5.1.11
 ufo2ft[pathops]==2.15.0
 defcon[lxml]==0.7.2
 skia-pathops==0.4.1
+gftools==0.7.0
 
 # only used for DesignSpaceDocumentReader in fontbuild
 MutatorMath==2.1.2