diff --git a/libbacktrace/ChangeLog b/libbacktrace/ChangeLog
index 89b690d415e9da603edb0630086612a517661244..0fa4bbb7ed88054537048286f59f76a423055015 100644
--- a/libbacktrace/ChangeLog
+++ b/libbacktrace/ChangeLog
@@ -1,3 +1,7 @@
+2020-05-13  Ian Lance Taylor  <iant@golang.org>
+
+	* ztest.c (test_large): Mark state ATTRIBUTE_UNUSED.
+
 2020-05-13  Ian Lance Taylor  <iant@golang.org>
 
 	PR go/95061
diff --git a/libbacktrace/ztest.c b/libbacktrace/ztest.c
index 2663c90061a1b7ae6c47ed7acbfcc229ad53c841..39476704972a8581386cec387fad051dc22404c2 100644
--- a/libbacktrace/ztest.c
+++ b/libbacktrace/ztest.c
@@ -294,7 +294,7 @@ average_time (const size_t *times, size_t trials)
 /* Test a larger text, if available.  */
 
 static void
-test_large (struct backtrace_state *state)
+test_large (struct backtrace_state *state ATTRIBUTE_UNUSED)
 {
 #ifdef HAVE_ZLIB
   unsigned char *orig_buf;