===================================================================
RCS file: /cvs/mandoc/tbl_layout.c,v
retrieving revision 1.10
retrieving revision 1.11
diff -u -p -r1.10 -r1.11
--- mandoc/tbl_layout.c	2011/01/04 23:48:39	1.10
+++ mandoc/tbl_layout.c	2011/01/07 13:03:48	1.11
@@ -1,4 +1,4 @@
-/*	$Id: tbl_layout.c,v 1.10 2011/01/04 23:48:39 schwarze Exp $ */
+/*	$Id: tbl_layout.c,v 1.11 2011/01/07 13:03:48 kristaps Exp $ */
 /*
  * Copyright (c) 2009, 2010 Kristaps Dzonsons <kristaps@bsd.lv>
  *
@@ -29,6 +29,12 @@ struct	tbl_phrase {
 	enum tbl_cellt	 key;
 };
 
+/*
+ * FIXME: we can make this parse a lot nicer by, when an error is
+ * encountered in a layout key, bailing to the next key (i.e. to the
+ * next whitespace then continuing).
+ */
+
 #define	KEYS_MAX	 11
 
 static	const struct tbl_phrase keys[KEYS_MAX] = {
@@ -173,8 +179,19 @@ cell(struct tbl_node *tbl, struct tbl_row *rp, 
 		return(0);
 	}
 
-	(*pos)++;
 	c = keys[i].key;
+
+	/*
+	 * If a span cell is found first, raise a warning and abort the
+	 * parse.  FIXME: recover from this somehow?
+	 */
+
+	if (NULL == rp->first && TBL_CELL_SPAN == c) {
+		TBL_MSG(tbl, MANDOCERR_TBLLAYOUT, ln, *pos);
+		return(0);
+	}
+
+	(*pos)++;
 
 	/* Extra check for the double-vertical. */