diff --git a/ChangeLog b/ChangeLog
index 2c2d5dab76..bee0173bb9 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Tue Dec  7 21:14:03 2010  Tanaka Akira  <akr@fsij.org>
+
+	* debug.c: parenthesize macro arguments.
+
 Tue Dec  7 21:06:38 2010  Kouhei Sutou  <kou@cozmixng.org>
 
 	* lib/rexml/doctype.rb, test/rexml/test_doctype.rb: suppress warnings.
diff --git a/debug.c b/debug.c
index 4959f922f6..dcc710bc4a 100644
--- a/debug.c
+++ b/debug.c
@@ -141,7 +141,7 @@ set_debug_option(const char *str, int len, void *arg)
 {
 #define SET_WHEN(name, var) do {	    \
 	if (len == sizeof(name) - 1 &&	    \
-	    strncmp(str, name, len) == 0) { \
+	    strncmp(str, (name), len) == 0) { \
 	    extern int var;	    \
 	    var = 1;		    \
 	    return;			    \