diff --git a/etc/taskcluster/decision_task.py b/etc/taskcluster/decision_task.py
index e5b16c5b952..89de61f9373 100644
--- a/etc/taskcluster/decision_task.py
+++ b/etc/taskcluster/decision_task.py
@@ -709,6 +709,7 @@ def macos_build_task(name):
             time brew bundle install --no-upgrade --file=etc/taskcluster/macos/Brewfile
             export OPENSSL_INCLUDE_DIR="$(brew --prefix openssl)/include"
             export OPENSSL_LIB_DIR="$(brew --prefix openssl)/lib"
+            export PKG_CONFIG_PATH="$(brew --prefix libffi)/lib/pkgconfig/"
         """)
 
         .with_directory_mount(