diff --git a/CHANGELOG b/CHANGELOG
index 0730e727d4..00bdf70895 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -50,6 +50,7 @@ Cacti CHANGELOG
 -issue#4551: PHP DEPRECATED errors in 8.1
 -issue#4552: Form error message not cleared before rendering forms leading to false error messages
 -issue#4554: PHP 8.1 Causing Automation Deprecation Errors
+-issue#4557: Undefined index in graph debug mode.
 -feature: Expose hidden Language Translation setting l10n_language_handler
 -feature: Allow a Device to be a part of a Report outside of a Tree
 -feature: Allow Basic Authentication to display customer login failed message
diff --git a/lib/functions.php b/lib/functions.php
index 73d5c0de29..2015b05659 100644
--- a/lib/functions.php
+++ b/lib/functions.php
@@ -2704,7 +2704,7 @@ function generate_graph_best_cf($local_data_id, $requested_cf, $ds_step = 60) {
 			/* workaround until we have RRA presets in 0.8.8 */
 			/* check through the cf's and get the best */
 			/* if none was found, take the first */
-			$best_cf = $avail_cf_functions[1];
+			$best_cf = reset($avail_cf_functions);
 
 			foreach($avail_cf_functions as $cf) {
 				if ($cf == $requested_cf) {