diff --git a/src/Symfony/Component/Yaml/Escaper.php b/src/Symfony/Component/Yaml/Escaper.php
index 150c5f6dad..78d93ddfe3 100644
--- a/src/Symfony/Component/Yaml/Escaper.php
+++ b/src/Symfony/Component/Yaml/Escaper.php
@@ -86,7 +86,7 @@ class Escaper
 
         // Determines if the PHP value contains any single characters that would
         // cause it to require single quoting in YAML.
-        return 0 < preg_match('/[ \s \' " \: \{ \} \[ \] , & \* \# \?] | \A[ \- ? | < > = ! % @ ` ]/x', $value);
+        return 0 < preg_match('/[ \s \' " \: \{ \} \[ \] , & \* \# \?] | \A[ \- ? | < > = ! % @ ` \p{Zs}]/xu', $value);
     }
 
     /**
diff --git a/src/Symfony/Component/Yaml/Tests/DumperTest.php b/src/Symfony/Component/Yaml/Tests/DumperTest.php
index 5bf0530220..41c8b02c7b 100644
--- a/src/Symfony/Component/Yaml/Tests/DumperTest.php
+++ b/src/Symfony/Component/Yaml/Tests/DumperTest.php
@@ -635,6 +635,21 @@ YAML;
     {
         $this->assertSame('{ foo: ~ }', $this->dumper->dump(['foo' => null], 0, 0, Yaml::DUMP_NULL_AS_TILDE));
     }
+
+    public function testDumpIdeographicSpaces()
+    {
+        $expected = <<<YAML
+alone: '　'
+within_string: 'a　b'
+regular_space: 'a b'
+
+YAML;
+        $this->assertSame($expected, $this->dumper->dump([
+            'alone' => '　',
+            'within_string' => 'a　b',
+            'regular_space' => 'a b',
+        ], 2));
+    }
 }
 
 class A
diff --git a/src/Symfony/Component/Yaml/Tests/InlineTest.php b/src/Symfony/Component/Yaml/Tests/InlineTest.php
index b4143b9c17..0f608c330c 100644
--- a/src/Symfony/Component/Yaml/Tests/InlineTest.php
+++ b/src/Symfony/Component/Yaml/Tests/InlineTest.php
@@ -511,6 +511,10 @@ class InlineTest extends TestCase
             ['"0123\r"', "0123\r"],
             ['"0123\t"', "0123\t"],
             ['"0123\v"', "0123\v"],
+
+            // whitespaces
+            'ideographic space' => ["'　'", '　'],
+            'ideographic space surrounded by characters' => ["'a　b'", 'a　b'],
         ];
     }