diff --git a/ChangeLog b/ChangeLog
index 784d13b08e..8abcabd580 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Fri Dec 10 22:33:39 2010  Tanaka Akira  <akr@fsij.org>
+
+	* dln_find.c: parenthesize macro arguments.
+
 Fri Dec 10 20:05:42 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* template/id.h.tmpl (ruby_method_ids): suppress warnings.
diff --git a/dln_find.c b/dln_find.c
index 305a7f2b7c..2873152587 100644
--- a/dln_find.c
+++ b/dln_find.c
@@ -57,7 +57,7 @@ void *xrealloc();
 #include <sys/stat.h>
 
 #ifndef S_ISDIR
-#   define S_ISDIR(m) ((m & S_IFMT) == S_IFDIR)
+#   define S_ISDIR(m) (((m) & S_IFMT) == S_IFDIR)
 #endif
 
 #ifdef HAVE_SYS_PARAM_H