diff --git a/lib/Cake/Model/Behavior/TreeBehavior.php b/lib/Cake/Model/Behavior/TreeBehavior.php
index e87abedc3..94c2bb443 100644
--- a/lib/Cake/Model/Behavior/TreeBehavior.php
+++ b/lib/Cake/Model/Behavior/TreeBehavior.php
@@ -682,7 +682,7 @@ class TreeBehavior extends ModelBehavior {
 		$children = $Model->find('all', $params);
 		$hasChildren = (bool)$children;
 
-		if (!is_null($parentId)) {
+		if ($parentId !== null) {
 			if ($hasChildren) {
 				$Model->updateAll(
 					array($this->settings[$Model->alias]['left'] => $counter),
@@ -713,7 +713,7 @@ class TreeBehavior extends ModelBehavior {
 			$children = $Model->find('all', $params);
 		}
 
-		if (!is_null($parentId) && $hasChildren) {
+		if ($parentId !== null && $hasChildren) {
 			$Model->updateAll(
 				array($this->settings[$Model->alias]['right'] => $counter),
 				array($Model->escapeField() => $parentId)
diff --git a/lib/Cake/Model/Model.php b/lib/Cake/Model/Model.php
index 670b71a6d..3b9563441 100644
--- a/lib/Cake/Model/Model.php
+++ b/lib/Cake/Model/Model.php
@@ -1849,7 +1849,7 @@ class Model extends Object implements CakeEventListener {
 				}
 
 				foreach ((array)$data as $row) {
-					if ((is_string($row) && (strlen($row) == 36 || strlen($row) == 16)) || is_numeric($row)) {
+					if ((is_string($row) && (strlen($row) === 36 || strlen($row) === 16)) || is_numeric($row)) {
 						$newJoins[] = $row;
 						$values = array($id, $row);
 						if ($isUUID && $primaryAdded) {
diff --git a/lib/Cake/Network/CakeResponse.php b/lib/Cake/Network/CakeResponse.php
index f6a0ed2e5..2f60667fe 100644
--- a/lib/Cake/Network/CakeResponse.php
+++ b/lib/Cake/Network/CakeResponse.php
@@ -570,7 +570,7 @@ class CakeResponse {
 			if (is_numeric($header)) {
 				list($header, $value) = array($value, null);
 			}
-			if (is_null($value)) {
+			if ($value === null) {
 				list($header, $value) = explode(':', $header, 2);
 			}
 			$this->_headers[$header] = is_array($value) ? array_map('trim', $value) : trim($value);
diff --git a/lib/Cake/Routing/Router.php b/lib/Cake/Routing/Router.php
index 375e08d3f..b91a6d5a6 100644
--- a/lib/Cake/Routing/Router.php
+++ b/lib/Cake/Routing/Router.php
@@ -1038,7 +1038,7 @@ class Router {
 		}
 		$addition = http_build_query($q, null, $join);
 
-		if ($out && $addition && substr($out, strlen($join) * -1, strlen($join)) != $join) {
+		if ($out && $addition && substr($out, strlen($join) * -1, strlen($join)) !== $join) {
 			$out .= $join;
 		}