diff --git a/meta-integrity/conf/layer.conf b/meta-integrity/conf/layer.conf
index 0a1deb8..8be64f6 100644
--- a/meta-integrity/conf/layer.conf
+++ b/meta-integrity/conf/layer.conf
@@ -24,7 +24,7 @@ LAYERRECOMMENDS_integrity = "\
     tpm \
 "
 
-BB_HASHBASE_WHITELIST += "\
+BB_HASHBASE_WHITELIST:append += "\
     RPM_FSK_PATH \
 "
 
diff --git a/meta-signing-key/conf/layer.conf b/meta-signing-key/conf/layer.conf
index 637fee3..77507b2 100644
--- a/meta-signing-key/conf/layer.conf
+++ b/meta-signing-key/conf/layer.conf
@@ -64,7 +64,7 @@ RPM_GPG_PASSPHRASE ??= "SecureCore"
 BOOT_GPG_NAME ??= "SecureBootCore"
 BOOT_GPG_PASSPHRASE ??= "SecureCore"
 
-BB_HASHBASE_WHITELIST += "\
+BB_HASHBASE_WHITELIST:append += "\
     SYSTEM_TRUSTED_KEYS_DIR \
     SECONDARY_TRUSTED_KEYS_DIR \
     MODSIGN_KEYS_DIR \