diff --git a/src/decl.c b/src/decl.c
index 758cca74e..43bca2d8e 100644
--- a/src/decl.c
+++ b/src/decl.c
@@ -24,7 +24,10 @@ NEARDATA int nroom = 0;
 NEARDATA int nsubroom = 0;
 NEARDATA int occtime = 0;
 
-int x_maze_max, y_maze_max;	/* initialized in main, used in mkmaze.c */
+/* maze limits must be even; masking off lowest bit guarantees that */
+int x_maze_max = (COLNO-1) & ~1,
+    y_maze_max = (ROWNO-1) & ~1;
+
 int otg_temp;			/* used by object_to_glyph() [otg] */
 
 #ifdef REDO
diff --git a/sys/be/bemain.c b/sys/be/bemain.c
index 3f67fc0c0..001d3ddf8 100644
--- a/sys/be/bemain.c
+++ b/sys/be/bemain.c
@@ -57,17 +57,6 @@ int MAIN(int argc, char **argv)
 
 	dlb_init();			/* must be before newgame() */
 
-	/*
-	 * Initialization of the boundaries of the mazes
-	 * Both boundaries have to be even.
-	 */
-	x_maze_max = COLNO-1;
-	if (x_maze_max % 2)
-		x_maze_max--;
-	y_maze_max = ROWNO-1;
-	if (y_maze_max % 2)
-		y_maze_max--;
-
 	/*
 	 * Initialize the vision system.  This must be before mklev() on a
 	 * new game or before a level restore on a saved game.
diff --git a/sys/mac/macmain.c b/sys/mac/macmain.c
index 0ad68009e..3293f46ed 100644
--- a/sys/mac/macmain.c
+++ b/sys/mac/macmain.c
@@ -46,18 +46,6 @@ main (void)
 	hname = "Mac Hack";
 	hackpid = getpid();
 
-	/*
-	 * Initialisation of the boundaries of the mazes
-	 * Both boundaries have to be even.
-	 */
-
-	x_maze_max = COLNO-1;
-	if (x_maze_max % 2)
-		x_maze_max--;
-	y_maze_max = ROWNO-1;
-	if (y_maze_max % 2)
-		y_maze_max--;
-
 	setrandom();
 	initoptions();
 	init_nhwindows(&argc, (char **)&hname);
diff --git a/sys/share/pcmain.c b/sys/share/pcmain.c
index bee05f9dc..9ef0cbf5d 100644
--- a/sys/share/pcmain.c
+++ b/sys/share/pcmain.c
@@ -415,18 +415,6 @@ char *argv[];
 	level_info[0].where = ACTIVE;
 #endif
 
-	/*
-	 * Initialisation of the boundaries of the mazes
-	 * Both boundaries have to be even.
-	 */
-
-	x_maze_max = COLNO-1;
-	if (x_maze_max % 2)
-		x_maze_max--;
-	y_maze_max = ROWNO-1;
-	if (y_maze_max % 2)
-		y_maze_max--;
-
 	/*
 	 *  Initialize the vision system.  This must be before mklev() on a
 	 *  new game or before a level restore on a saved game.
diff --git a/sys/unix/unixmain.c b/sys/unix/unixmain.c
index 81b033cef..4a70d666d 100644
--- a/sys/unix/unixmain.c
+++ b/sys/unix/unixmain.c
@@ -231,17 +231,6 @@ char *argv[];
 
 	dlb_init();	/* must be before newgame() */
 
-	/*
-	 * Initialization of the boundaries of the mazes
-	 * Both boundaries have to be even.
-	 */
-	x_maze_max = COLNO-1;
-	if (x_maze_max % 2)
-		x_maze_max--;
-	y_maze_max = ROWNO-1;
-	if (y_maze_max % 2)
-		y_maze_max--;
-
 	/*
 	 *  Initialize the vision system.  This must be before mklev() on a
 	 *  new game or before a level restore on a saved game.
diff --git a/sys/vms/vmsmain.c b/sys/vms/vmsmain.c
index 9c6474891..d1ab5f7d4 100644
--- a/sys/vms/vmsmain.c
+++ b/sys/vms/vmsmain.c
@@ -158,17 +158,6 @@ char *argv[];
 
 	dlb_init();	/* must be before newgame() */
 
-	/*
-	 * Initialization of the boundaries of the mazes
-	 * Both boundaries have to be even.
-	 */
-	x_maze_max = COLNO-1;
-	if (x_maze_max % 2)
-		x_maze_max--;
-	y_maze_max = ROWNO-1;
-	if (y_maze_max % 2)
-		y_maze_max--;
-
 	/*
 	 *  Initialize the vision system.  This must be before mklev() on a
 	 *  new game or before a level restore on a saved game.