diff --git a/application/palemoon/confvars.sh b/application/palemoon/confvars.sh
index 9eac7f93a..3f2212d7a 100644
--- a/application/palemoon/confvars.sh
+++ b/application/palemoon/confvars.sh
@@ -48,6 +48,8 @@ MOZ_PERSONAS=1
 
 # Enable SQL storage format for certs and passwords in NSS
 MOZ_SECURITY_SQLSTORE=1
+# ...and explicitly disable the legacy DBM format.
+NSS_DISABLE_DBM=1
 
 # Browser Feature: Profile Migration Component
 MOZ_PROFILE_MIGRATOR=