diff --git a/src/feature.h b/src/feature.h
index e31e463..b9a8f79 100644
--- a/src/feature.h
+++ b/src/feature.h
@@ -1194,6 +1194,7 @@
 /*
  * These features can only be included by using a configure argument.  See the
  * Makefile for a line to uncomment.
+ * +lua                 Lua interface: "--enable-luainterp"
  * +mzscheme		MzScheme interface: "--enable-mzscheme"
  * +perl		Perl interface: "--enable-perlinterp"
  * +python		Python interface: "--enable-pythoninterp"