diff --git a/src/Manipulators/Brightness.php b/src/Manipulators/Brightness.php
index f1d44971..2a33544e 100644
--- a/src/Manipulators/Brightness.php
+++ b/src/Manipulators/Brightness.php
@@ -5,7 +5,7 @@
 use Intervention\Image\Image;
 
 /**
- * @property string $bri
+ * @property string|null $bri
  */
 class Brightness extends BaseManipulator
 {
@@ -34,7 +34,7 @@ public function run(Image $image)
      */
     public function getBrightness()
     {
-        if (!preg_match('/^-*[0-9]+$/', $this->bri)) {
+        if (null === $this->bri || !preg_match('/^-*[0-9]+$/', $this->bri)) {
             return;
         }
 
diff --git a/src/Manipulators/Contrast.php b/src/Manipulators/Contrast.php
index 38fc35c9..c2cf9140 100644
--- a/src/Manipulators/Contrast.php
+++ b/src/Manipulators/Contrast.php
@@ -5,7 +5,7 @@
 use Intervention\Image\Image;
 
 /**
- * @property string $con
+ * @property string|null $con
  */
 class Contrast extends BaseManipulator
 {
@@ -34,7 +34,7 @@ public function run(Image $image)
      */
     public function getContrast()
     {
-        if (!preg_match('/^-*[0-9]+$/', $this->con)) {
+        if (null === $this->con || !preg_match('/^-*[0-9]+$/', $this->con)) {
             return;
         }
 
diff --git a/src/Manipulators/Crop.php b/src/Manipulators/Crop.php
index 78cfc228..9a8428df 100644
--- a/src/Manipulators/Crop.php
+++ b/src/Manipulators/Crop.php
@@ -5,7 +5,7 @@
 use Intervention\Image\Image;
 
 /**
- * @property string $crop
+ * @property string|null $crop
  */
 class Crop extends BaseManipulator
 {
@@ -45,6 +45,10 @@ public function run(Image $image)
      */
     public function getCoordinates(Image $image)
     {
+        if (null === $this->crop) {
+            return;
+        }
+
         $coordinates = explode(',', $this->crop);
 
         if (4 !== count($coordinates) or
diff --git a/src/Manipulators/Gamma.php b/src/Manipulators/Gamma.php
index 2242a909..035bb8de 100644
--- a/src/Manipulators/Gamma.php
+++ b/src/Manipulators/Gamma.php
@@ -5,7 +5,7 @@
 use Intervention\Image\Image;
 
 /**
- * @property string $gam
+ * @property string|null $gam
  */
 class Gamma extends BaseManipulator
 {
@@ -34,7 +34,7 @@ public function run(Image $image)
      */
     public function getGamma()
     {
-        if (!preg_match('/^[0-9]\.*[0-9]*$/', $this->gam)) {
+        if (null === $this->gam || !preg_match('/^[0-9]\.*[0-9]*$/', $this->gam)) {
             return;
         }
 
diff --git a/src/Manipulators/Size.php b/src/Manipulators/Size.php
index 68493634..b5308829 100644
--- a/src/Manipulators/Size.php
+++ b/src/Manipulators/Size.php
@@ -5,10 +5,10 @@
 use Intervention\Image\Image;
 
 /**
- * @property string $dpr
- * @property string $fit
- * @property string $h
- * @property string $w
+ * @property string      $dpr
+ * @property string|null $fit
+ * @property string      $h
+ * @property string      $w
  */
 class Size extends BaseManipulator
 {
@@ -119,6 +119,10 @@ public function getHeight()
      */
     public function getFit()
     {
+        if (null === $this->fit) {
+            return 'contain';
+        }
+
         if (in_array($this->fit, ['contain', 'fill', 'max', 'stretch'], true)) {
             return $this->fit;
         }
@@ -424,6 +428,10 @@ public function getCrop()
             'crop-bottom-right' => [100, 100, 1.0],
         ];
 
+        if (null === $this->fit) {
+            return [50, 50, 1.0];
+        }
+
         if (array_key_exists($this->fit, $cropMethods)) {
             return $cropMethods[$this->fit];
         }
diff --git a/src/ServerFactory.php b/src/ServerFactory.php
index a6819a29..778e7da0 100644
--- a/src/ServerFactory.php
+++ b/src/ServerFactory.php
@@ -57,13 +57,13 @@ public function getServer()
             $this->getApi()
         );
 
-        $server->setSourcePathPrefix($this->getSourcePathPrefix());
-        $server->setCachePathPrefix($this->getCachePathPrefix());
+        $server->setSourcePathPrefix($this->getSourcePathPrefix() ?: '');
+        $server->setCachePathPrefix($this->getCachePathPrefix() ?: '');
         $server->setGroupCacheInFolders($this->getGroupCacheInFolders());
         $server->setCacheWithFileExtensions($this->getCacheWithFileExtensions());
         $server->setDefaults($this->getDefaults());
         $server->setPresets($this->getPresets());
-        $server->setBaseUrl($this->getBaseUrl());
+        $server->setBaseUrl($this->getBaseUrl() ?: '');
         $server->setResponseFactory($this->getResponseFactory());
 
         if ($this->getTempDir()) {
@@ -259,7 +259,7 @@ public function getManipulators()
             new Flip(),
             new Blur(),
             new Pixelate(),
-            new Watermark($this->getWatermarks(), $this->getWatermarksPathPrefix()),
+            new Watermark($this->getWatermarks(), $this->getWatermarksPathPrefix() ?: ''),
             new Background(),
             new Border(),
             new Encode(),