diff --git a/runtime/mercury_deep_profiling.c b/runtime/mercury_deep_profiling.c
index 7d537e79b..0f60a94c9 100644
--- a/runtime/mercury_deep_profiling.c
+++ b/runtime/mercury_deep_profiling.c
@@ -1,7 +1,7 @@
 // vim: ts=4 sw=4 expandtab ft=c
 
 // Copyright (C) 2001-2008, 2010-2011 The University of Melbourne.
-// Copyright (C) 2016, 2018 The Mercury team.
+// Copyright (C) 2016, 2018-2019, 2022, 2024 The Mercury team.
 // This file is distributed under the terms specified in COPYING.LIB.
 
 // Deep profiling module
@@ -228,7 +228,7 @@ MR_deep_profile_update_special_history(void)
 }
 
 void
-MR_deep_profile_update_closure_history()
+MR_deep_profile_update_closure_history(void)
 {
     if (MR_deep_prof_search_len < MR_MAX_CLOSURE_LIST_LENGTH) {
         MR_closure_search_lengths[MR_deep_prof_search_len]++;
@@ -236,7 +236,7 @@ MR_deep_profile_update_closure_history()
 }
 
 void
-MR_deep_profile_update_method_history()
+MR_deep_profile_update_method_history(void)
 {
     if (MR_deep_prof_search_len < MR_MAX_CLOSURE_LIST_LENGTH) {
         MR_method_search_lengths[MR_deep_prof_search_len]++;
diff --git a/runtime/mercury_memory_zones.c b/runtime/mercury_memory_zones.c
index 179b2840f..db7dc3e59 100644
--- a/runtime/mercury_memory_zones.c
+++ b/runtime/mercury_memory_zones.c
@@ -1,7 +1,7 @@
 // vim: ts=4 sw=4 expandtab ft=c
 
 // Copyright (C) 1998-2000, 2002-2007, 2010-2012 The University of Melbourne.
-// Copyright (C) 2013-2016, 2018 The Mercury team.
+// Copyright (C) 2013-2016, 2018, 2022, 2024 The Mercury team.
 // This file is distributed under the terms specified in COPYING.LIB.
 
 // This module defines the MR_MemoryZone data structure and operations
@@ -343,7 +343,7 @@ static MR_MemoryZone * MR_THREADSAFE_VOLATILE used_memory_zones = NULL;
 #endif
 
 void
-MR_init_zones()
+MR_init_zones(void)
 {
 #ifdef  MR_THREAD_SAFE
     pthread_mutex_init(&memory_zones_lock, MR_MUTEX_ATTR);
@@ -359,7 +359,7 @@ MR_init_zones()
 }
 
 static void
-MR_init_offsets()
+MR_init_offsets(void)
 {
     int     i;
     size_t  fake_reg_offset;
diff --git a/runtime/mercury_trace_base.c b/runtime/mercury_trace_base.c
index 7b007e011..0be07d429 100644
--- a/runtime/mercury_trace_base.c
+++ b/runtime/mercury_trace_base.c
@@ -1,7 +1,7 @@
 // vim: ts=4 sw=4 expandtab ft=c
 
 // Copyright (C) 1997-2008, 2011 The University of Melbourne.
-// Copyright (C) 2014-2016, 2018, 2022-2023 The Mercury team.
+// Copyright (C) 2014-2016, 2018, 2022-2024 The Mercury team.
 // This file is distributed under the terms specified in COPYING.LIB.
 
 // mercury_trace_base.c implements the interface between the main part
@@ -588,7 +588,7 @@ MR_trace_write_label_exec_counts_for_file(FILE *fp,
 }
 
 void
-MR_trace_name_count_port_ensure_init()
+MR_trace_name_count_port_ensure_init(void)
 {
     static MR_bool  done = MR_FALSE;