diff --git a/ChangeLog b/ChangeLog
index b2a115f3..d7db9317 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2006-02-13  Paul Eggert  <eggert@cs.ucla.edu>
+
+	* configure.ac (AC_INIT): Bump version number.
+
 2006-02-13  Paul Eggert  <eggert@cs.ucla.edu>
 
 	* NEWS: Version 2.1a.
diff --git a/configure.ac b/configure.ac
index 39b19178..087cd490 100644
--- a/configure.ac
+++ b/configure.ac
@@ -24,7 +24,7 @@
 # least Autoconf 2.59.
 AC_PREREQ(2.59)
 
-AC_INIT([GNU Bison], [2.1a], [bug-bison@gnu.org])
+AC_INIT([GNU Bison], [2.1b], [bug-bison@gnu.org])
 AC_CONFIG_AUX_DIR([build-aux])
 AC_CONFIG_MACRO_DIR([m4])