diff --git a/CHANGES b/CHANGES
index 31439f4..9cd77be 100644
--- a/CHANGES
+++ b/CHANGES
@@ -4,7 +4,7 @@
 * https://github.com/yaml/pyyaml/commits/
 * https://bitbucket.org/xi/pyyaml/commits/
 
-5.1 (2019-02-24)
+5.1b1 (2019-02-24)
 ----------------
 
 * https://github.com/yaml/pyyaml/pull/35  -- Some modernization of the test running
diff --git a/announcement.msg b/announcement.msg
index 0d245ca..9fdff04 100644
--- a/announcement.msg
+++ b/announcement.msg
@@ -3,9 +3,15 @@
 Subject: [ANN] PyYAML-5.1: YAML parser and emitter for Python
 
 =======================
- Announcing PyYAML-5.1
+ Announcing PyYAML-5.1b1 (First beta release)
 =======================
 
+The first beta release of PyYAML-5.1 has been uploaded to pypi.org. The final
+release is expected to land in the next 2 weeks. Normally we would only
+announce the final release, but this one has been a long time coming and has
+major changes, so we want people to know about the release process early on.
+
+
 A new MAJOR RELEASE of PyYAML is now available:
 https://pypi.org/project/PyYAML/
 
diff --git a/lib/yaml/__init__.py b/lib/yaml/__init__.py
index 8b372a2..f3aed76 100644
--- a/lib/yaml/__init__.py
+++ b/lib/yaml/__init__.py
@@ -8,7 +8,7 @@
 from loader import *
 from dumper import *
 
-__version__ = '5.1'
+__version__ = '5.1b1'
 
 try:
     from cyaml import *
diff --git a/lib3/yaml/__init__.py b/lib3/yaml/__init__.py
index deb0d58..e3ad70f 100644
--- a/lib3/yaml/__init__.py
+++ b/lib3/yaml/__init__.py
@@ -8,7 +8,7 @@
 from .loader import *
 from .dumper import *
 
-__version__ = '5.1'
+__version__ = '5.1b1'
 try:
     from .cyaml import *
     __with_libyaml__ = True
diff --git a/setup.py b/setup.py
index f40a5c4..9571168 100644
--- a/setup.py
+++ b/setup.py
@@ -1,6 +1,6 @@
 
 NAME = 'PyYAML'
-VERSION = '5.1'
+VERSION = '5.1b1'
 DESCRIPTION = "YAML parser and emitter for Python"
 LONG_DESCRIPTION = """\
 YAML is a data serialization format designed for human readability