diff --git make-ca-clean/make-ca make-ca-workdir/make-ca
index a7663be..f00ad05 100644
--- make-ca-clean/make-ca
+++ make-ca-workdir/make-ca
@@ -15,7 +15,7 @@ VERSION="1.13"
 MAKE_CA_CONF="/etc/make-ca.conf"
 
 # CA root for hg.mozilla.org
-MOZILLA_CA_ROOT="/etc/make-ca/mozilla-ca-root.pem"
+MOZILLA_CA_ROOT="${MOZILLA_CERT_SYSROOT}/etc/make-ca/mozilla-ca-root.pem"
 
 # Get/set defaults
 if test -f "${MAKE_CA_CONF}"; then