diff --git a/DataStorage/Database/Query/Builder.php b/DataStorage/Database/Query/Builder.php
index 9766b4412..1ffccdac0 100644
--- a/DataStorage/Database/Query/Builder.php
+++ b/DataStorage/Database/Query/Builder.php
@@ -356,17 +356,8 @@ class Builder extends BuilderAbstract
      */
     public function raw(string $raw) : Builder
     {
-        if ($this->isReadOnly) {
-            $test = strtolower($raw);
-
-            if (strpos($test, 'insert') !== false 
-            || strpos($test, 'update') !== false
-            || strpos($test, 'drop') !== false
-            || strpos($test, 'delete') !== false
-            || strpos($test, 'create') !== false
-            || strpos($test, 'alter') !== false) {
-                throw new \Exception();
-            }
+        if (!$this->isValidReadOnly($raw)) {
+            throw new \Exception();
         }
 
         $this->type = QueryType::RAW;
@@ -375,6 +366,37 @@ class Builder extends BuilderAbstract
         return $this;
     }
 
+    /**
+     * Tests if a string contains a non read only component in case the builder is read only.
+     * If the builder is not read only it will always return true
+     *
+     * @param  string $raw Raw query
+     *
+     * @return bool
+     *
+     * @since  1.0.0
+     */
+    private function isValidReadOnly($raw) : bool
+    {
+        if (!$this->isReadOnly) {
+            return true;
+        }
+
+        $test = strtolower($raw);
+
+        if (strpos($test, 'insert') !== false 
+            || strpos($test, 'update') !== false
+            || strpos($test, 'drop') !== false
+            || strpos($test, 'delete') !== false
+            || strpos($test, 'create') !== false
+            || strpos($test, 'alter') !== false
+        ) {
+            return false;
+        }
+
+        return true;
+    }
+
     /**
      * Make raw column selection.
      *
@@ -459,36 +481,31 @@ class Builder extends BuilderAbstract
      */
     public function where($columns, $operator = null, $values = null, $boolean = 'and') : Builder
     {
-        // TODO: handle $value is null -> operator NULL
         if (isset($operator) && !is_array($operator) && !in_array(strtolower($operator), self::OPERATORS)) {
             throw new \InvalidArgumentException('Unknown operator.');
         }
 
-        if (is_array($columns)) {
-            $i = 0;
-            foreach ($columns as $key => $column) {
-                if (isset($operator[$i]) && !in_array(strtolower($operator[$i]), self::OPERATORS)) {
-                    throw new \InvalidArgumentException('Unknown operator.');
-                }
+        if (is_string($columns)) {
+            $colums = [$columns];
+            $operator = [$operator];
+            $values = [$values];
+            $boolean = [$boolean];
+        }
 
-                $this->wheres[self::getPublicColumnName($column)][] = [
-                    'column'   => $column,
-                    'operator' => $operator[$i],
-                    'value'    => $values[$i],
-                    'boolean'  => $boolean[$i],
-                ];
-
-                $i++;
-            }
-        } elseif (is_string($columns)) {
-            if (isset($operator) && !in_array(strtolower($operator), self::OPERATORS)) {
+        $i = 0;
+        foreach ($columns as $key => $column) {
+            if (isset($operator[$i]) && !in_array(strtolower($operator[$i]), self::OPERATORS)) {
                 throw new \InvalidArgumentException('Unknown operator.');
             }
 
-            $this->wheres[self::getPublicColumnName($columns)][] = ['column'  => $columns, 'operator' => $operator, 'value' => $values,
-                                     'boolean' => $boolean,];
-        } else {
-            throw new \InvalidArgumentException();
+            $this->wheres[self::getPublicColumnName($column)][] = [
+                'column'   => $column,
+                'operator' => $operator[$i],
+                'value'    => $values[$i],
+                'boolean'  => $boolean[$i],
+            ];
+
+            $i++;
         }
 
         return $this;
diff --git a/Message/Http/Header.php b/Message/Http/Header.php
index bebc3c445..131725aca 100644
--- a/Message/Http/Header.php
+++ b/Message/Http/Header.php
@@ -71,18 +71,18 @@ class Header extends HeaderAbstract
             throw new LockException('HTTP header');
         }
 
+        if (self::isSecurityHeader($key) && isset($this->header[$key])) {
+            throw new \Exception('Cannot change security headers.');
+        }
+
         $key = strtolower($key);
 
         if (!$overwrite && isset($this->header[$key])) {
             return false;
-        } elseif ($overwrite || !isset($this->header[$key])) {
-            if (self::isSecurityHeader($key) && isset($this->header[$key])) {
-                throw new \Exception('Cannot change security headers.');
-            }
-
-            unset($this->header[$key]);
         }
 
+        unset($this->header[$key]);
+
         if (!isset($this->header[$key])) {
             $this->header[$key] = [];
         }