diff --git a/build b/build
index 3241cb4..9d07984 100755
--- a/build
+++ b/build
@@ -57,7 +57,7 @@ BR2_TARGET_ROOTFS_INITRAMFS=n
       j="$OPTARG"
       ;;
     K)
-      linux_kernel_custom_config_file="$OPTARG"
+      linux_kernel_custom_config_file="$(common_abspath "${OPTARG}")"
       ;;
     k)
       extra_make_args="${extra_make_args} kernel_module-reconfigure \\
@@ -130,11 +130,10 @@ BR2_ROOTFS_POST_SCRIPT_ARGS=\"${post_script_args}\"
     printf "BR2_PACKAGE_GEM5=y\n" >> "${config_file}"
   fi
   if [ -n "$linux_kernel_custom_config_file" ]; then
-    f="../${linux_kernel_custom_config_file}"
-    if [ -f "$f" ]; then
-      printf "BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE=\"${f}\"\n" >> "$config_file"
+    if [ -f "$linux_kernel_custom_config_file" ]; then
+      printf "BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE=\"${linux_kernel_custom_config_file}\"\n" >> "$config_file"
       if "${linux_reconfigure}"; then
-        touch "$f"
+        touch "${linux_kernel_custom_config_file}"
       fi
     else
       echo "error: -K: file does not exist: ${linux_kernel_custom_config_file}" 1>&2