diff --git a/src/backend/postmaster/autovacuum.c b/src/backend/postmaster/autovacuum.c
index 1792008ebe..47b4bacadb 100644
--- a/src/backend/postmaster/autovacuum.c
+++ b/src/backend/postmaster/autovacuum.c
@@ -311,7 +311,7 @@ NON_EXEC_STATIC void AutoVacLauncherMain(int argc, char *argv[]) pg_attribute_no
 
 static Oid	do_start_worker(void);
 static void HandleAutoVacLauncherInterrupts(void);
-static void AutoVacLauncherShutdown() pg_attribute_noreturn();
+static void AutoVacLauncherShutdown(void) pg_attribute_noreturn();
 static void launcher_determine_sleep(bool canlaunch, bool recursing,
 									 struct timeval *nap);
 static void launch_worker(TimestampTz now);
@@ -828,7 +828,7 @@ HandleAutoVacLauncherInterrupts(void)
  * Perform a normal exit from the autovac launcher.
  */
 static void
-AutoVacLauncherShutdown()
+AutoVacLauncherShutdown(void)
 {
 	ereport(DEBUG1,
 			(errmsg("autovacuum launcher shutting down")));
diff --git a/src/backend/postmaster/checkpointer.c b/src/backend/postmaster/checkpointer.c
index 3f35b324c3..df527ac021 100644
--- a/src/backend/postmaster/checkpointer.c
+++ b/src/backend/postmaster/checkpointer.c
@@ -161,7 +161,7 @@ static pg_time_t last_xlog_switch_time;
 
 /* Prototypes for private functions */
 
-static void HandleCheckpointerInterrupts();
+static void HandleCheckpointerInterrupts(void);
 static void CheckArchiveTimeout(void);
 static bool IsCheckpointOnSchedule(double progress);
 static bool ImmediateCheckpointRequested(void);