Test if value is instance of \Closure

framework/grid/DataColumn.php

@@ -141,7 +141,7 @@ class DataColumn extends Column
 	protected function renderDataCellContent($model, $key, $index)
 	{
 		if ($this->value !== null) {
-		if (is_callable($this->value)) {
+			if ($this->value instanceof \Closure) {
 				$value = call_user_func($this->value, $model, $index, $this);
 			} else {
 				$value = ArrayHelper::getValue($model, $this->value);