diff --git a/ChangeLog b/ChangeLog
index 3bcce1d479..deece5f208 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Mon Jan 17 22:54:33 2011  Tanaka Akira  <akr@fsij.org>
+
+	* debug.h: parenthesize macro arguments.
+
 Mon Jan 17 21:40:25 2011  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* ruby.c (process_options): revert r30549.
diff --git a/debug.h b/debug.h
index cc85a550f1..f1d11304f0 100644
--- a/debug.h
+++ b/debug.h
@@ -19,10 +19,10 @@
 #pragma GCC visibility push(default)
 #endif
 
-#define dpv(h,v) ruby_debug_print_value(-1, 0, h, v)
-#define dp(v)    ruby_debug_print_value(-1, 0, "", v)
-#define dpi(i)   ruby_debug_print_id(-1, 0, "", i)
-#define dpn(n)   ruby_debug_print_node(-1, 0, "", n)
+#define dpv(h,v) ruby_debug_print_value(-1, 0, (h), (v))
+#define dp(v)    ruby_debug_print_value(-1, 0, "", (v))
+#define dpi(i)   ruby_debug_print_id(-1, 0, "", (i))
+#define dpn(n)   ruby_debug_print_node(-1, 0, "", (n))
 
 #define bp()     ruby_debug_breakpoint()