diff --git a/lib/dns/config/confcommon.c b/lib/dns/config/confcommon.c
index f1b803654c..7690196ef1 100644
--- a/lib/dns/config/confcommon.c
+++ b/lib/dns/config/confcommon.c
@@ -145,7 +145,7 @@ static struct dns_c_pvt_cntable {
 
 isc_boolean_t debug_mem_print;
 FILE *debug_mem_print_stream;
-struct in6_addr in6addr_any;
+const struct in6_addr in6addr_any;
 
 
 
diff --git a/lib/dns/include/dns/confcommon.h b/lib/dns/include/dns/confcommon.h
index 77d94b5d27..fdc17ab908 100644
--- a/lib/dns/include/dns/confcommon.h
+++ b/lib/dns/include/dns/confcommon.h
@@ -253,7 +253,7 @@ typedef struct dns_c_addr {
 extern isc_boolean_t debug_mem_print;
 extern FILE *debug_mem_print_stream;	/* NULL means stderr */
 
-extern struct in6_addr in6addr_any;	/* all 0 bits wildcard addr. */
+extern const struct in6_addr in6addr_any;	/* all 0 bits wildcard addr. */
 
 typedef void (*dns_cfg_err_handler_t)(isc_result_t code,
 				      const char *fmt, va_list args);