diff --git a/etc/taskcluster/decision_task.py b/etc/taskcluster/decision_task.py
index e2288f45366..72e62985356 100644
--- a/etc/taskcluster/decision_task.py
+++ b/etc/taskcluster/decision_task.py
@@ -909,6 +909,7 @@ def macos_build_task(name):
             export OPENSSL_INCLUDE_DIR="$(brew --prefix openssl)/include"
             export OPENSSL_LIB_DIR="$(brew --prefix openssl)/lib"
             export PKG_CONFIG_PATH="$(brew --prefix libffi)/lib/pkgconfig/"
+            export PKG_CONFIG_PATH="$(brew --prefix zlib)/lib/pkgconfig/:$PKG_CONFIG_PATH"
         """)
 
         .with_directory_mount(
diff --git a/etc/taskcluster/macos/Brewfile b/etc/taskcluster/macos/Brewfile
index d13b3cfa678..ab177ef32d6 100644
--- a/etc/taskcluster/macos/Brewfile
+++ b/etc/taskcluster/macos/Brewfile
@@ -5,6 +5,7 @@ brew "openssl"
 brew "pkg-config"
 brew "llvm"
 brew "yasm"
+brew "zlib"
 
 # For sccache
 brew "openssl@1.1"