diff --git a/README.md b/README.md
index a95d76a..4c7df1c 100644
--- a/README.md
+++ b/README.md
@@ -48,12 +48,12 @@ A more complicated example:
 
 Streaming serialization with file-like objects:
 ``` python
->>> f = open('test.bin', 'w')
+>>> f = open('test.bin', 'wb')
 >>> umsgpack.pack({u"compact": True, u"schema": 0}, f)
 >>> umsgpack.pack([1,2,3], f)
 >>> f.close()
 >>> 
->>> f = open('test.bin')
+>>> f = open('test.bin', 'rb')
 >>> umsgpack.unpack(f)
 {u'compact': True, u'schema': 0}
 >>> umsgpack.unpack(f)
@@ -87,11 +87,11 @@ Python standard library style names `dump`, `dumps`, `load`, `loads` are also av
 >>> umsgpack.loads(_)
 {u'compact': True, u'schema': 0}
 >>> 
->>> f = open('test.bin', 'w')
+>>> f = open('test.bin', 'wb')
 >>> umsgpack.dump({u"compact": True, u"schema": 0}, f)
 >>> f.close()
 >>> 
->>> f = open('test.bin')
+>>> f = open('test.bin', 'rb')
 >>> umsgpack.load(f)
 {u'compact': True, u'schema': 0}
 >>> 
diff --git a/msgpack.org.md b/msgpack.org.md
index d8a53b2..7cd2c1b 100644
--- a/msgpack.org.md
+++ b/msgpack.org.md
@@ -49,12 +49,12 @@ A more complicated example:
 
 Streaming serialization with file-like objects:
 ``` python
->>> f = open('test.bin', 'w')
+>>> f = open('test.bin', 'wb')
 >>> umsgpack.pack({u"compact": True, u"schema": 0}, f)
 >>> umsgpack.pack([1,2,3], f)
 >>> f.close()
 >>> 
->>> f = open('test.bin')
+>>> f = open('test.bin', 'rb')
 >>> umsgpack.unpack(f)
 {u'compact': True, u'schema': 0}
 >>> umsgpack.unpack(f)
@@ -89,11 +89,11 @@ available:
 >>> umsgpack.loads(_)
 {u'compact': True, u'schema': 0}
 >>> 
->>> f = open('test.bin', 'w')
+>>> f = open('test.bin', 'wb')
 >>> umsgpack.dump({u"compact": True, u"schema": 0}, f)
 >>> f.close()
 >>> 
->>> f = open('test.bin')
+>>> f = open('test.bin', 'rb')
 >>> umsgpack.load(f)
 {u'compact': True, u'schema': 0}
 >>>