diff --git a/inc/topo.h b/inc/topo.h
index e2b1e7e..b6bcce8 100644
--- a/inc/topo.h
+++ b/inc/topo.h
@@ -10,16 +10,16 @@ extern "C" {
 struct topo_desc;
 
 int
-topo_num_core();
+topo_num_core(void);
 
 int
-topo_num_numa();
+topo_num_numa(void);
 
 int
 topo_core_to_numa(int coreid);
 
 void
-topo_destroy();
+topo_destroy(void);
 
 int
 topo_init(int enable_alloc, int verbose);
diff --git a/topo.c b/topo.c
index 41be77c..892a291 100644
--- a/topo.c
+++ b/topo.c
@@ -417,13 +417,13 @@ desc_init(struct topo_desc * desc, int enable_alloc, int verbose)
 // public APIs
 //
 int
-topo_num_core()
+topo_num_core(void)
 {
     return g_default_desc.num_core;
 }
 
 int
-topo_num_numa()
+topo_num_numa(void)
 {
     return g_default_desc.num_numa;
 }
@@ -435,7 +435,7 @@ topo_core_to_numa(int coreid)
 }
 
 void
-topo_destroy()
+topo_destroy(void)
 {
     desc_destroy(&g_default_desc);
 }
@@ -453,7 +453,7 @@ topo_free(unsigned int node, void * addr)
 }
 
 uint64_t
-topo_uptime_ns()
+topo_uptime_ns(void)
 {
     return topo_desc_uptime_ns(&g_default_desc);
 }