diff --git a/include/osmocom/vty/command.h b/include/osmocom/vty/command.h
index caf0414..08819d1 100644
--- a/include/osmocom/vty/command.h
+++ b/include/osmocom/vty/command.h
@@ -316,7 +316,7 @@
 void install_default(enum node_type);
 void install_element(enum node_type, struct cmd_element *);
 void install_element_ve(struct cmd_element *cmd);
-void sort_node();
+void sort_node(void);
 
 /* Concatenates argv[shift] through argv[argc-1] into a single NUL-terminated
    string with a space between each element (allocated using