diff --git a/core/modules/migrate/src/Plugin/migrate/source/SqlBase.php b/core/modules/migrate/src/Plugin/migrate/source/SqlBase.php
index 415033b..3b60058 100644
--- a/core/modules/migrate/src/Plugin/migrate/source/SqlBase.php
+++ b/core/modules/migrate/src/Plugin/migrate/source/SqlBase.php
@@ -107,7 +107,7 @@ protected function prepareQuery() {
     // keys, so throw an exception if the key is multi-value.
     if (isset($this->configuration['idlist'])) {
       $key = $this->getIds();
-      if (sizeof($key) == 1) {
+      if (count($key) == 1) {
         $field = key($key);
         // If a table alias was provided, prepend it in order to prevent
         // the possibility of 'ambiguous column' errors.