diff --git a/ChangeLog b/ChangeLog
index 5885507bb5..d57c03bfde 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+Fri Nov 11 21:00:05 2011  Tanaka Akira  <akr@fsij.org>
+
+	* ext/dbm/extconf.rb: fix dbm_pagfno and dbm_dirfno detection with
+	  Berkeley DB.  Macro definitions needs arguments to detect correctly.
+	  SIZEOF_DSIZE needs -DDB_DBM_HSEARCH because db.h defines datum type
+	  only if DB_DBM_HSEARCH is defined. 
+
 Fri Nov 11 18:41:57 2011  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* process.c (proc_seteuid): separate an internal wrapper function
diff --git a/ext/dbm/extconf.rb b/ext/dbm/extconf.rb
index fb722a3c39..608f4d472f 100644
--- a/ext/dbm/extconf.rb
+++ b/ext/dbm/extconf.rb
@@ -64,12 +64,12 @@ end
 if dblib.any? {|db| headers.db_check(db)}
   have_header("cdefs.h")
   have_header("sys/cdefs.h")
-  have_func("dbm_pagfno", headers.found, headers.defs)
-  have_func("dbm_dirfno", headers.found, headers.defs)
+  have_func("dbm_pagfno((DBM *)0)", headers.found, headers.defs)
+  have_func("dbm_dirfno((DBM *)0)", headers.found, headers.defs)
   type = checking_for "sizeof(datum.dsize)", STRING_OR_FAILED_FORMAT do
     pre = headers.found + [["static datum conftest_key;"]]
     %w[int long LONG_LONG].find do |t|
-      try_static_assert("sizeof(conftest_key.dsize) <= sizeof(#{t})", pre)
+      try_static_assert("sizeof(conftest_key.dsize) <= sizeof(#{t})", pre, headers.defs)
     end
   end
   $defs << "-DSIZEOF_DSIZE=SIZEOF_"+type.tr_cpp if type