diff --git a/src/Symfony/Component/Serializer/Encoder/CsvEncoder.php b/src/Symfony/Component/Serializer/Encoder/CsvEncoder.php
index 1e47d35f17c7f..e887b03d54a06 100644
--- a/src/Symfony/Component/Serializer/Encoder/CsvEncoder.php
+++ b/src/Symfony/Component/Serializer/Encoder/CsvEncoder.php
@@ -189,11 +189,36 @@ private function flatten(array $array, array &$result, $keySeparator, $parentKey
             if (\is_array($value)) {
                 $this->flatten($value, $result, $keySeparator, $parentKey.$key.$keySeparator);
             } else {
-                $result[$parentKey.$key] = $value;
+                $result[$parentKey.$key] = $this->cleanValueByType($value);
             }
         }
     }
 
+    /**
+     * Ensures an actual value is used instead of a blank value when dealing
+     * with true, false and null (like a nullable bool in a database).
+     *
+     * @param string $value
+     *
+     * @return string
+     */
+    private function cleanValueByType($value)
+    {
+        $clean = $value;
+
+        if (false === $value) {
+            $clean = 0;
+        } elseif (null === $value) {
+            // fputcsv will enclose a space
+            // https://github.com/php/php-src/blob/master/ext/standard/file.c
+            $clean = ' ';
+        } elseif (true === $value) {
+            $clean = 1;
+        }
+
+        return $clean;
+    }
+
     private function getCsvOptions(array $context)
     {
         $delimiter = isset($context[self::DELIMITER_KEY]) ? $context[self::DELIMITER_KEY] : $this->delimiter;
diff --git a/src/Symfony/Component/Serializer/Tests/Encoder/CsvEncoderTest.php b/src/Symfony/Component/Serializer/Tests/Encoder/CsvEncoderTest.php
index 1eb673e8e21ba..a3a13f47f9edf 100644
--- a/src/Symfony/Component/Serializer/Tests/Encoder/CsvEncoderTest.php
+++ b/src/Symfony/Component/Serializer/Tests/Encoder/CsvEncoderTest.php
@@ -29,6 +29,25 @@ protected function setUp()
         $this->encoder = new CsvEncoder();
     }
 
+    public function testTrueFalseNullValues()
+    {
+        $data = [
+            'string' => 'foo',
+            'int' => 2,
+            'false' => false,
+            'true' => true,
+            'null' => null,
+        ];
+
+        // Check that true, false and null are appropriately handled
+        $this->assertEquals(<<<'CSV'
+string,int,false,true,null
+foo,2,0,1," "
+
+CSV
+    , $this->encoder->encode($data, 'csv'));
+    }
+
     public function testSupportEncoding()
     {
         $this->assertTrue($this->encoder->supportsEncoding('csv'));