diff --git a/lib/yaml/emitter.py b/lib/yaml/emitter.py
index e5bcdccc..5fb4179a 100644
--- a/lib/yaml/emitter.py
+++ b/lib/yaml/emitter.py
@@ -8,9 +8,13 @@
 
 __all__ = ['Emitter', 'EmitterError']
 
+import sys
+
 from error import YAMLError
 from events import *
 
+has_ucs4 = sys.maxunicode > 0xffff
+
 class EmitterError(YAMLError):
     pass
 
@@ -674,7 +678,7 @@ def analyze_scalar(self, scalar):
             # Check for indicators.
             if index == 0:
                 # Leading indicators are special characters.
-                if ch in u'#,[]{}&*!|>\'\"%@`': 
+                if ch in u'#,[]{}&*!|>\'\"%@`':
                     flow_indicators = True
                     block_indicators = True
                 if ch in u'?:':
@@ -701,7 +705,8 @@ def analyze_scalar(self, scalar):
                 line_breaks = True
             if not (ch == u'\n' or u'\x20' <= ch <= u'\x7E'):
                 if (ch == u'\x85' or u'\xA0' <= ch <= u'\uD7FF'
-                        or u'\uE000' <= ch <= u'\uFFFD') and ch != u'\uFEFF':
+                        or u'\uE000' <= ch <= u'\uFFFD'
+                        or ((not has_ucs4) or (u'\U00010000' <= ch < u'\U0010ffff'))) and ch != u'\uFEFF':
                     unicode_characters = True
                     if not self.allow_unicode:
                         special_characters = True
@@ -1137,4 +1142,3 @@ def write_plain(self, text, split=True):
                 spaces = (ch == u' ')
                 breaks = (ch in u'\n\x85\u2028\u2029')
             end += 1
-
diff --git a/lib/yaml/reader.py b/lib/yaml/reader.py
index 3249e6b9..56a12f48 100644
--- a/lib/yaml/reader.py
+++ b/lib/yaml/reader.py
@@ -19,7 +19,9 @@
 
 from error import YAMLError, Mark
 
-import codecs, re
+import codecs, re, sys
+
+has_ucs4 = sys.maxunicode > 0xffff
 
 class ReaderError(YAMLError):
 
@@ -134,7 +136,10 @@ def determine_encoding(self):
                 self.encoding = 'utf-8'
         self.update(1)
 
-    NON_PRINTABLE = re.compile(u'[^\x09\x0A\x0D\x20-\x7E\x85\xA0-\uD7FF\uE000-\uFFFD]')
+    if has_ucs4:
+        NON_PRINTABLE = re.compile(u'[^\x09\x0A\x0D\x20-\x7E\x85\xA0-\uD7FF\uE000-\uFFFD\U00010000-\U0010ffff]')
+    else:
+        NON_PRINTABLE = re.compile(u'[^\x09\x0A\x0D\x20-\x7E\x85\xA0-\uD7FF\uE000-\uFFFD]')
     def check_printable(self, data):
         match = self.NON_PRINTABLE.search(data)
         if match:
@@ -187,4 +192,3 @@ def update_raw(self, size=1024):
 #    psyco.bind(Reader)
 #except ImportError:
 #    pass
-
diff --git a/lib3/yaml/emitter.py b/lib3/yaml/emitter.py
index 34cb145a..34798834 100644
--- a/lib3/yaml/emitter.py
+++ b/lib3/yaml/emitter.py
@@ -671,7 +671,7 @@ def analyze_scalar(self, scalar):
             # Check for indicators.
             if index == 0:
                 # Leading indicators are special characters.
-                if ch in '#,[]{}&*!|>\'\"%@`': 
+                if ch in '#,[]{}&*!|>\'\"%@`':
                     flow_indicators = True
                     block_indicators = True
                 if ch in '?:':
@@ -698,7 +698,8 @@ def analyze_scalar(self, scalar):
                 line_breaks = True
             if not (ch == '\n' or '\x20' <= ch <= '\x7E'):
                 if (ch == '\x85' or '\xA0' <= ch <= '\uD7FF'
-                        or '\uE000' <= ch <= '\uFFFD') and ch != '\uFEFF':
+                        or '\uE000' <= ch <= '\uFFFD'
+                        or '\U00010000' <= ch < '\U0010ffff') and ch != '\uFEFF':
                     unicode_characters = True
                     if not self.allow_unicode:
                         special_characters = True
@@ -1134,4 +1135,3 @@ def write_plain(self, text, split=True):
                 spaces = (ch == ' ')
                 breaks = (ch in '\n\x85\u2028\u2029')
             end += 1
-
diff --git a/lib3/yaml/reader.py b/lib3/yaml/reader.py
index f70e920f..376b9a36 100644
--- a/lib3/yaml/reader.py
+++ b/lib3/yaml/reader.py
@@ -134,7 +134,7 @@ def determine_encoding(self):
                 self.encoding = 'utf-8'
         self.update(1)
 
-    NON_PRINTABLE = re.compile('[^\x09\x0A\x0D\x20-\x7E\x85\xA0-\uD7FF\uE000-\uFFFD]')
+    NON_PRINTABLE = re.compile('[^\x09\x0A\x0D\x20-\x7E\x85\xA0-\uD7FF\uE000-\uFFFD\U00010000-\U0010ffff]')
     def check_printable(self, data):
         match = self.NON_PRINTABLE.search(data)
         if match:
@@ -189,4 +189,3 @@ def update_raw(self, size=4096):
 #    psyco.bind(Reader)
 #except ImportError:
 #    pass
-