diff --git a/src/config.h b/src/config.h
index 8f4c40c..06dcbfe 100644
--- a/src/config.h
+++ b/src/config.h
@@ -5,6 +5,7 @@ static const unsigned int borderpx	= 4;		/* border pixel of windows */
 static const unsigned int snap		= 16;		/* snap pixel (32)*/
 static const unsigned int gappx		= 0;
 static const unsigned int gappx2	= 40;
+static const unsigned int gapmodes[] = { 0, 40 };
 static const int showbar			= 1;		/* 0 means no bar */
 static const int topbar				= 0;		/* 0 means bottom bar */
 static const int usealtbar			= 1;		/* 1 means use non-dwm status bar */
diff --git a/src/dwm.c b/src/dwm.c
index 383160c..f13bf6a 100644
--- a/src/dwm.c
+++ b/src/dwm.c
@@ -137,6 +137,7 @@ struct Monitor {
 	int mx, my, mw, mh;   /* screen size */
 	int wx, wy, ww, wh;   /* window area  */
 	int gappx;            /* gaps between windows */
+	unsigned int gapidx;	/* gap mode index */
 	unsigned int seltags;
 	unsigned int sellt;
 	unsigned int tagset[2];