diff --git a/src/filters.c b/src/filters.c
index e27505040..07b904316 100644
--- a/src/filters.c
+++ b/src/filters.c
@@ -142,6 +142,9 @@ flt_dump_kws(char **out)
 	struct flt_kw_list *kwl;
 	int index;
 
+	if (!out)
+		return;
+
 	*out = NULL;
 	list_for_each_entry(kwl, &flt_keywords.list, list) {
 		for (index = 0; kwl->kw[index].kw != NULL; index++) {
diff --git a/src/listener.c b/src/listener.c
index 829dc99b7..01feee58f 100644
--- a/src/listener.c
+++ b/src/listener.c
@@ -1255,6 +1255,9 @@ void bind_dump_kws(char **out)
 	struct bind_kw_list *kwl;
 	int index;
 
+	if (!out)
+		return;
+
 	*out = NULL;
 	list_for_each_entry(kwl, &bind_keywords.list, list) {
 		for (index = 0; kwl->kw[index].kw != NULL; index++) {
diff --git a/src/server.c b/src/server.c
index 265106eb8..e4044cd7a 100644
--- a/src/server.c
+++ b/src/server.c
@@ -247,6 +247,9 @@ void srv_dump_kws(char **out)
 	struct srv_kw_list *kwl;
 	int index;
 
+	if (!out)
+		return;
+
 	*out = NULL;
 	list_for_each_entry(kwl, &srv_keywords.list, list) {
 		for (index = 0; kwl->kw[index].kw != NULL; index++) {