diff --git a/docs/HISTORY.md b/docs/HISTORY.md
index 11ceb85..38c8f15 100644
--- a/docs/HISTORY.md
+++ b/docs/HISTORY.md
@@ -1,5 +1,10 @@
 # MongoDB Ruby Driver History
 
+### 1.5.0.rc0
+2011-11-18
+
+Fix bugs associated with replica set refresh.
+
 ### 1.4.1
 2011-10-17
 
diff --git a/ext/cbson/version.h b/ext/cbson/version.h
index 3f49969..66e6595 100644
--- a/ext/cbson/version.h
+++ b/ext/cbson/version.h
@@ -14,4 +14,4 @@
  * limitations under the License.
  */
 
-#define VERSION "1.4.1"
+#define VERSION "1.5.0.rc0"
diff --git a/lib/bson.rb b/lib/bson.rb
index 206a27e..efa7157 100644
--- a/lib/bson.rb
+++ b/lib/bson.rb
@@ -18,10 +18,10 @@
 
 $:.unshift(File.join(File.dirname(__FILE__), '..', 'lib'))
 
-MINIMUM_BSON_EXT_VERSION = "1.4.1"
+MINIMUM_BSON_EXT_VERSION = "1.5.0.rc0"
 
 module BSON
-  VERSION = "1.4.1"
+  VERSION = "1.5.0.rc0"
 
   if defined? Mongo::DEFAULT_MAX_BSON_SIZE
     DEFAULT_MAX_BSON_SIZE = Mongo::DEFAULT_MAX_BSON_SIZE
diff --git a/lib/mongo/version.rb b/lib/mongo/version.rb
index 1f51e16..3d79882 100644
--- a/lib/mongo/version.rb
+++ b/lib/mongo/version.rb
@@ -1,3 +1,3 @@
 module Mongo
-  VERSION = "1.4.1"
+  VERSION = "1.5.0.rc0"
 end