diff --git a/attn/meson.build b/attn/meson.build
index 3b085af..9397274 100644
--- a/attn/meson.build
+++ b/attn/meson.build
@@ -6,6 +6,13 @@
 # dependency to link gpiod support
 libgpiod = dependency('libgpiod', version : '>=1.4.1')
 
+# ENABLE_PHAL_TRUE used in attn_handler.service
+if (get_option('phal').enabled())
+    configuration_data().set('ENABLE_PHAL_TRUE', '')
+else
+    configuration_data().set('ENABLE_PHAL_TRUE', '#')
+endif
+
 # install systemd unit file
 configure_file(
     input: 'attn_handler.service',