diff --git a/sys/powerpc/aim/mp_cpudep.c b/sys/powerpc/aim/mp_cpudep.c
--- a/sys/powerpc/aim/mp_cpudep.c
+++ b/sys/powerpc/aim/mp_cpudep.c
@@ -306,7 +306,7 @@
 }
 
 void
-cpudep_ap_setup()
+cpudep_ap_setup(void)
 {
 #ifndef __powerpc64__
 	register_t	reg;
diff --git a/sys/powerpc/ofw/ofw_machdep.c b/sys/powerpc/ofw/ofw_machdep.c
--- a/sys/powerpc/ofw/ofw_machdep.c
+++ b/sys/powerpc/ofw/ofw_machdep.c
@@ -598,7 +598,7 @@
 }
 
 boolean_t
-OF_bootstrap()
+OF_bootstrap(void)
 {
 	boolean_t status = FALSE;
 	int err = 0;
@@ -809,7 +809,7 @@
 }
 
 void
-OF_reboot()
+OF_reboot(void)
 {
 	struct {
 		cell_t name;
diff --git a/sys/powerpc/powerpc/cpu.c b/sys/powerpc/powerpc/cpu.c
--- a/sys/powerpc/powerpc/cpu.c
+++ b/sys/powerpc/powerpc/cpu.c
@@ -267,7 +267,7 @@
  * so they can be used during platform and MMU bringup.
  */
 void
-cpu_feature_setup()
+cpu_feature_setup(void)
 {
 	u_int		pvr;
 	uint16_t	vers;
diff --git a/sys/powerpc/powerpc/fpu.c b/sys/powerpc/powerpc/fpu.c
--- a/sys/powerpc/powerpc/fpu.c
+++ b/sys/powerpc/powerpc/fpu.c
@@ -213,7 +213,7 @@
  * Clear Floating-Point Status and Control Register
  */
 void
-cleanup_fpscr()
+cleanup_fpscr(void)
 {
 	register_t msr;
 
diff --git a/sys/powerpc/powerpc/platform.c b/sys/powerpc/powerpc/platform.c
--- a/sys/powerpc/powerpc/platform.c
+++ b/sys/powerpc/powerpc/platform.c
@@ -247,7 +247,7 @@
 }
 
 const char *
-installed_platform()
+installed_platform(void)
 {
 	return (plat_def_impl->name);
 }
@@ -262,7 +262,7 @@
  * Put the current CPU, as last step in suspend, to sleep
  */
 void
-platform_sleep()
+platform_sleep(void)
 {
         PLATFORM_SLEEP(plat_obj);
 }
@@ -292,7 +292,7 @@
 }
 
 void
-platform_smp_ap_init()
+platform_smp_ap_init(void)
 {
 	PLATFORM_SMP_AP_INIT(plat_obj);
 }
@@ -321,7 +321,7 @@
  * Reset back to firmware.
  */
 void
-cpu_reset()
+cpu_reset(void)
 {
         PLATFORM_RESET(plat_obj);
 }
@@ -339,7 +339,7 @@
 SET_DECLARE(platform_set, platform_def_t);
 
 void
-platform_probe_and_attach()
+platform_probe_and_attach(void)
 {
 	platform_def_t	**platpp, *platp;
 	int		prio, best_prio;
diff --git a/sys/powerpc/powerpc/pmap_dispatch.c b/sys/powerpc/powerpc/pmap_dispatch.c
--- a/sys/powerpc/powerpc/pmap_dispatch.c
+++ b/sys/powerpc/powerpc/pmap_dispatch.c
@@ -224,7 +224,7 @@
 
 /* MMU "pre-bootstrap" init, used to install extra resolvers, etc. */
 void
-pmap_mmu_init()
+pmap_mmu_init(void)
 {
 	if (mmu_obj->funcs->install != NULL)
 		(mmu_obj->funcs->install)();
diff --git a/sys/powerpc/ps3/mmu_ps3.c b/sys/powerpc/ps3/mmu_ps3.c
--- a/sys/powerpc/ps3/mmu_ps3.c
+++ b/sys/powerpc/ps3/mmu_ps3.c
@@ -91,7 +91,7 @@
 static struct mtx mps3_table_lock;
 
 static void
-mps3_install()
+mps3_install(void)
 {
 	moea64_ops = &mps3_funcs;
 	moea64_install();
diff --git a/sys/powerpc/pseries/mmu_phyp.c b/sys/powerpc/pseries/mmu_phyp.c
--- a/sys/powerpc/pseries/mmu_phyp.c
+++ b/sys/powerpc/pseries/mmu_phyp.c
@@ -124,7 +124,7 @@
     NULL);
 
 static void
-mphyp_install()
+mphyp_install(void)
 {
 	char buf[8];
 	uint32_t prop[2];