diff --git a/configure.ac b/configure.ac
index 9377774..56ee544 100644
--- a/configure.ac
+++ b/configure.ac
@@ -181,6 +181,9 @@
 	      enable_headless_compositor=yes)
 AM_CONDITIONAL(ENABLE_HEADLESS_COMPOSITOR,
 	       test x$enable_headless_compositor = xyes)
+if test x$enable_headless_compositor = xyes; then
+  AC_DEFINE([BUILD_HEADLESS_COMPOSITOR], [1], [Build the headless compositor])
+fi
 
 
 AC_ARG_ENABLE(rpi-compositor,