diff --git a/configure b/configure
index 07cb7b412a..03162008aa 100755
--- a/configure
+++ b/configure
@@ -3963,6 +3963,10 @@ for rom in seabios; do
     echo "RANLIB=$ranlib" >> $config_mak
 done
 
+config_mak=pc-bios/optionrom/config.mak
+echo "# Automatically generated by configure - do not modify" > $config_mak
+echo "TOPSRC_DIR=$source_path" >> $config_mak
+
 if test "$skip_meson" = no; then
   cross="config-meson.cross.new"
   meson_quote() {
diff --git a/pc-bios/optionrom/Makefile b/pc-bios/optionrom/Makefile
index 30771f8d17..3482508a86 100644
--- a/pc-bios/optionrom/Makefile
+++ b/pc-bios/optionrom/Makefile
@@ -1,6 +1,5 @@
-CURRENT_MAKEFILE := $(realpath $(word $(words $(MAKEFILE_LIST)),$(MAKEFILE_LIST)))
-SRC_DIR := $(dir $(CURRENT_MAKEFILE))
-TOPSRC_DIR := $(SRC_DIR)/../..
+include config.mak
+SRC_DIR := $(TOPSRC_DIR)/pc-bios/optionrom
 VPATH = $(SRC_DIR)
 
 all: multiboot.bin linuxboot.bin linuxboot_dma.bin kvmvapic.bin pvh.bin