diff --git a/doc/Changelog b/doc/Changelog
index 69558ddf1..4ab938aeb 100644
--- a/doc/Changelog
+++ b/doc/Changelog
@@ -9,6 +9,7 @@
 	- random generator cleanup - RND_STATE_SIZE removed, and instead
 	  a super-rnd can be passed at init to chain init random states.
 	- test also does lock checks if available.
+	- protect config access in libworker_setup().
 
 25 January 2008: Wouter
 	- added tpkg for asynclook and library use. 
diff --git a/libunbound/worker.c b/libunbound/worker.c
index 009e08b8f..6b55b1d58 100644
--- a/libunbound/worker.c
+++ b/libunbound/worker.c
@@ -108,8 +108,14 @@ libworker_setup(struct ub_val_ctx* ctx, int is_bg)
 	}
 	w->thread_num = w->env->alloc->thread_num;
 	alloc_set_id_cleanup(w->env->alloc, &libworker_alloc_cleanup, w);
+	if(!w->is_bg || w->is_bg_thread) {
+		lock_basic_lock(&ctx->cfglock);
+	}
 	w->env->scratch = regional_create_custom(cfg->msg_buffer_size);
 	w->env->scratch_buffer = ldns_buffer_new(cfg->msg_buffer_size);
+	if(!w->is_bg || w->is_bg_thread) {
+		lock_basic_unlock(&ctx->cfglock);
+	}
 	if(!w->env->scratch || !w->env->scratch_buffer) {
 		libworker_delete(w);
 		return NULL;
@@ -139,11 +145,17 @@ libworker_setup(struct ub_val_ctx* ctx, int is_bg)
 		libworker_delete(w);
 		return NULL;
 	}
+	if(!w->is_bg || w->is_bg_thread) {
+		lock_basic_lock(&ctx->cfglock);
+	}
 	w->back = outside_network_create(w->base, cfg->msg_buffer_size,
 		(size_t)cfg->outgoing_num_ports, cfg->out_ifs,
 		cfg->num_out_ifs, cfg->do_ip4, cfg->do_ip6, -1, 
 		cfg->do_tcp?cfg->outgoing_num_tcp:0,
 		w->env->infra_cache, w->env->rnd);
+	if(!w->is_bg || w->is_bg_thread) {
+		lock_basic_unlock(&ctx->cfglock);
+	}
 	if(!w->back) {
 		libworker_delete(w);
 		return NULL;
diff --git a/testdata/05-asynclook.tpkg b/testdata/05-asynclook.tpkg
index df7e08888..1fd0e332f 100644
Binary files a/testdata/05-asynclook.tpkg and b/testdata/05-asynclook.tpkg differ