diff --git a/lib/isc/pthreads/thread.c b/lib/isc/pthreads/thread.c
index 48a0c4a161..71bada9be1 100644
--- a/lib/isc/pthreads/thread.c
+++ b/lib/isc/pthreads/thread.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2004, 2005, 2007, 2013, 2017  Internet Systems Consortium, Inc. ("ISC")
+ * Copyright (C) 2004, 2005, 2007, 2013, 2017, 2018  Internet Systems Consortium, Inc. ("ISC")
  * Copyright (C) 2000, 2001, 2003  Internet Software Consortium.
  *
  * Permission to use, copy, modify, and/or distribute this software for any
@@ -37,7 +37,10 @@ isc_thread_create(isc_threadfunc_t func, isc_threadarg_t arg,
 		  isc_thread_t *thread)
 {
 	pthread_attr_t attr;
+#if defined(HAVE_PTHREAD_ATTR_GETSTACKSIZE) && \
+    defined(HAVE_PTHREAD_ATTR_SETSTACKSIZE)
 	size_t stacksize;
+#endif
 	int ret;
 
 	pthread_attr_init(&attr);
diff --git a/util/copyrights b/util/copyrights
index 8d03935738..20af8a1cc6 100644
--- a/util/copyrights
+++ b/util/copyrights
@@ -3779,7 +3779,7 @@
 ./lib/isc/pthreads/include/isc/once.h		C	1999,2000,2001,2004,2005,2007
 ./lib/isc/pthreads/include/isc/thread.h		C	1998,1999,2000,2001,2004,2005,2007,2013,2017
 ./lib/isc/pthreads/mutex.c			C	2000,2001,2002,2004,2005,2007,2008,2011,2012,2014,2015
-./lib/isc/pthreads/thread.c			C	2000,2001,2003,2004,2005,2007,2013,2017
+./lib/isc/pthreads/thread.c			C	2000,2001,2003,2004,2005,2007,2013,2017,2018
 ./lib/isc/quota.c				C	2000,2001,2004,2005,2007
 ./lib/isc/radix.c				C	2007,2008,2009,2011,2012,2013,2014,2016
 ./lib/isc/random.c				C	1999,2000,2001,2002,2003,2004,2005,2007,2009,2013,2014,2016,2017