diff --git a/doxygenConfig b/doxygenConfig
index 9c458df7a2a13..9d4bbfbe246a3 100644
--- a/doxygenConfig
+++ b/doxygenConfig
@@ -3,7 +3,7 @@
 #---------------------------------------------------------------------------
 DOXYFILE_ENCODING      = UTF-8
 PROJECT_NAME           = MongoDB
-PROJECT_NUMBER         = 1.6.5
+PROJECT_NUMBER         = 1.6.6-pre-
 OUTPUT_DIRECTORY       = docs/doxygen
 CREATE_SUBDIRS         = NO
 OUTPUT_LANGUAGE        = English
diff --git a/util/version.cpp b/util/version.cpp
index 8421e16acaf02..c5ca8d40d1b85 100644
--- a/util/version.cpp
+++ b/util/version.cpp
@@ -14,7 +14,7 @@ namespace mongo {
     // mongo processes version support
     //
 
-    const char versionString[] = "1.6.5";
+    const char versionString[] = "1.6.6-pre-";
 
     string mongodVersion() {
         stringstream ss;