diff --git a/runoff b/runoff
index 21ee8ed..0e0e49e 100755
--- a/runoff
+++ b/runoff
@@ -89,16 +89,17 @@ perl -e '
 				print STDERR "Have no toc for $file\n";
 				next;
 			}
-			# this assumes that sheet 1 of code is a left page
-			# double-check the PDF
+			# this assumes that sheet 1 of code is a right page
+			# double-check the PDF.  swap the two regexps below
+			# otherwise.
 			if(!$leftwarn++) {
-				print STDERR "assuming that sheet 1 is a left page.  double-check!\n";
+				print STDERR "assuming that sheet 1 is a right page.  double-check!\n";
 			}
-			if($what eq "left" && !($toc{$file} =~ /^\d[13579]0/)){
+			if($what eq "left" && !($toc{$file} =~ /^\d[02468]0/)){
 				print STDERR "$file does not start on a fresh left page [$toc{$file}]\n";
 			}
 			# why does this not work if I inline $x in the if?
-			$x = ($toc{$file} =~ /^\d[02468]0/);
+			$x = ($toc{$file} =~ /^\d[13579]0/);
 			if($what eq "right" && !$x){
 				print STDERR "$file does not start on a fresh right page [$toc{$file}] [$x]\n";
 			}