diff --git a/meson.build b/meson.build
index 0385027..746ce47 100644
--- a/meson.build
+++ b/meson.build
@@ -2432,8 +2432,8 @@
 endif
 
 fdt = not_found
-fdt_opt = get_option('fdt')
 if have_system
+  fdt_opt = get_option('fdt')
   if fdt_opt in ['enabled', 'auto', 'system']
     have_internal = fs.exists(meson.current_source_dir() / 'dtc/libfdt/Makefile.libfdt')
     fdt = cc.find_library('fdt', kwargs: static_kwargs,
@@ -2476,6 +2476,8 @@
     fdt = declare_dependency(link_with: libfdt,
                              include_directories: fdt_inc)
   endif
+else
+  fdt_opt = 'disabled'
 endif
 if not fdt.found() and fdt_required.length() > 0
   error('fdt not available but required by targets ' + ', '.join(fdt_required))