diff --git a/tools/testing/ktest/ktest.pl b/tools/testing/ktest/ktest.pl
index 1fd29b2daa92..8dc8c3cf3acf 100755
--- a/tools/testing/ktest/ktest.pl
+++ b/tools/testing/ktest/ktest.pl
@@ -1638,7 +1638,7 @@ sub run_config_bisect {
 	if (!$found) {
 	    # try the other half
 	    doprint "Top half produced no set configs, trying bottom half\n";
-	    @tophalf = @start_list[$half .. $#start_list];
+	    @tophalf = @start_list[$half + 1 .. $#start_list];
 	    create_config @tophalf;
 	    read_current_config \%current_config;
 	    foreach my $config (@tophalf) {
@@ -1690,7 +1690,7 @@ sub run_config_bisect {
 	# remove half the configs we are looking at and see if
 	# they are good.
 	$half = int($#start_list / 2);
-    } while ($half > 0);
+    } while ($#start_list > 0);
 
     # we found a single config, try it again unless we are running manually