diff --git a/application/libraries/Availability.php b/application/libraries/Availability.php
index 0372e380..fef7300e 100644
--- a/application/libraries/Availability.php
+++ b/application/libraries/Availability.php
@@ -127,11 +127,16 @@ class Availability {
         $date_working_plan = $working_plan[$working_day] ?? NULL;
 
         // Search if the $date is a custom availability period added outside the normal working plan.
-        if (isset($working_plan_exceptions[$date]))
+        if (array_key_exists($date, $working_plan_exceptions))
         {
             $date_working_plan = $working_plan_exceptions[$date];
         }
 
+        if ( ! $date_working_plan)
+        {
+            return [];
+        }
+
         $periods = [];
 
         if (isset($date_working_plan['breaks']))
@@ -374,7 +379,7 @@ class Availability {
         $date_working_plan = $working_plan[$working_day] ?? NULL;
 
         // Search if the $date is a custom availability period added outside the normal working plan.
-        if (isset($working_plan_exceptions[$date]))
+        if (array_key_exists($date, $working_plan_exceptions))
         {
             $date_working_plan = $working_plan_exceptions[$date];
         }
diff --git a/application/models/Providers_model.php b/application/models/Providers_model.php
index 21c3438b..583f8120 100755
--- a/application/models/Providers_model.php
+++ b/application/models/Providers_model.php
@@ -636,7 +636,7 @@ class Providers_model extends EA_Model {
 
         $working_plan_exceptions = json_decode($provider['settings']['working_plan_exceptions'], TRUE);
 
-        if ( ! isset($working_plan_exceptions[$date]))
+        if ( ! array_key_exists($date, $working_plan_exceptions))
         {
             return; // The selected date does not exist in provider's settings.
         }