diff --git a/build.config.gki.aarch64 b/build.config.gki.aarch64
index 337ea8aaace1..3069101736a6 100644
--- a/build.config.gki.aarch64
+++ b/build.config.gki.aarch64
@@ -3,5 +3,6 @@
 . ${ROOT_DIR}/${KERNEL_DIR}/build.config.gki
 
 if [ -n "${GKI_BUILD_CONFIG_FRAGMENT}" ]; then
-source ${GKI_BUILD_CONFIG_FRAGMENT}
+    echo "ERROR: GKI_BUILD_CONFIG_FRAGMENT is deprecated; use --gki_build_config_fragment instead.">&2
+    exit 1
 fi
diff --git a/build.config.gki.x86_64 b/build.config.gki.x86_64
index 6d6a98dc28be..d679a20eff43 100644
--- a/build.config.gki.x86_64
+++ b/build.config.gki.x86_64
@@ -3,5 +3,6 @@
 . ${ROOT_DIR}/${KERNEL_DIR}/build.config.gki
 
 if [ -n "${GKI_BUILD_CONFIG_FRAGMENT}" ]; then
-source ${GKI_BUILD_CONFIG_FRAGMENT}
+    echo "ERROR: GKI_BUILD_CONFIG_FRAGMENT is deprecated; use --gki_build_config_fragment instead.">&2
+    exit 1
 fi