diff --git a/ChangeLog b/ChangeLog
index 0ce786a569..72f0592f2c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Sun Mar 13 18:11:28 2011  Tanaka Akira  <akr@fsij.org>
+
+	* ext/openssl/ossl_x509attr.c: parenthesize macro arguments.
+
 Sun Mar 13 16:07:58 2011  Shota Fukumori  <sorah@tubusu.net>
 
 	* lib/pstore.rb: Fix don't raise "nested transaction" when thread_safe
diff --git a/ext/openssl/ossl_x509attr.c b/ext/openssl/ossl_x509attr.c
index 1ab13692d4..1f36ca8b12 100644
--- a/ext/openssl/ossl_x509attr.c
+++ b/ext/openssl/ossl_x509attr.c
@@ -11,20 +11,20 @@
 #include "ossl.h"
 
 #define WrapX509Attr(klass, obj, attr) do { \
-    if (!attr) { \
+    if (!(attr)) { \
 	ossl_raise(rb_eRuntimeError, "ATTR wasn't initialized!"); \
     } \
-    obj = Data_Wrap_Struct(klass, 0, X509_ATTRIBUTE_free, attr); \
+    (obj) = Data_Wrap_Struct((klass), 0, X509_ATTRIBUTE_free, (attr)); \
 } while (0)
 #define GetX509Attr(obj, attr) do { \
-    Data_Get_Struct(obj, X509_ATTRIBUTE, attr); \
-    if (!attr) { \
+    Data_Get_Struct((obj), X509_ATTRIBUTE, (attr)); \
+    if (!(attr)) { \
 	ossl_raise(rb_eRuntimeError, "ATTR wasn't initialized!"); \
     } \
 } while (0)
 #define SafeGetX509Attr(obj, attr) do { \
-    OSSL_Check_Kind(obj, cX509Attr); \
-    GetX509Attr(obj, attr); \
+    OSSL_Check_Kind((obj), cX509Attr); \
+    GetX509Attr((obj), (attr)); \
 } while (0)
 
 /*