diff --git a/pgxn/neon/walproposer.h b/pgxn/neon/walproposer.h
index 41daeb87b9..20dce6f53c 100644
--- a/pgxn/neon/walproposer.h
+++ b/pgxn/neon/walproposer.h
@@ -725,7 +725,7 @@ extern void WalProposerBroadcast(WalProposer *wp, XLogRecPtr startpos, XLogRecPt
 extern void WalProposerPoll(WalProposer *wp);
 extern void WalProposerFree(WalProposer *wp);
 
-extern WalproposerShmemState *GetWalpropShmemState();
+extern WalproposerShmemState *GetWalpropShmemState(void);
 
 /*
  * WaitEventSet API doesn't allow to remove socket, so walproposer_pg uses it to
diff --git a/pgxn/neon/walproposer_pg.c b/pgxn/neon/walproposer_pg.c
index 01f88a5ab3..218277c7ed 100644
--- a/pgxn/neon/walproposer_pg.c
+++ b/pgxn/neon/walproposer_pg.c
@@ -538,7 +538,7 @@ nwp_shmem_startup_hook(void)
 }
 
 WalproposerShmemState *
-GetWalpropShmemState()
+GetWalpropShmemState(void)
 {
 	Assert(walprop_shared != NULL);
 	return walprop_shared;
diff --git a/pgxn/neon_walredo/walredoproc.c b/pgxn/neon_walredo/walredoproc.c
index 6a656c8d38..4487fa0140 100644
--- a/pgxn/neon_walredo/walredoproc.c
+++ b/pgxn/neon_walredo/walredoproc.c
@@ -136,7 +136,7 @@ static bool redo_block_filter(XLogReaderState *record, uint8 block_id);
 static void GetPage(StringInfo input_message);
 static void Ping(StringInfo input_message);
 static ssize_t buffered_read(void *buf, size_t count);
-static void CreateFakeSharedMemoryAndSemaphores();
+static void CreateFakeSharedMemoryAndSemaphores(void);
 
 static BufferTag target_redo_tag;
 
@@ -449,7 +449,7 @@ WalRedoMain(int argc, char *argv[])
  * half-initialized postgres.
  */
 static void
-CreateFakeSharedMemoryAndSemaphores()
+CreateFakeSharedMemoryAndSemaphores(void)
 {
 	PGShmemHeader *shim = NULL;
 	PGShmemHeader *hdr;