diff --git a/src/light.c b/src/light.c
index 0f7273282..ec6bda128 100644
--- a/src/light.c
+++ b/src/light.c
@@ -47,8 +47,8 @@ static void write_ls(NHFILE *, light_source *);
 static int maybe_write_ls(NHFILE *, int, boolean);
 
 /* imported from vision.c, for small circles */
-extern coordxy circle_data[];
-extern coordxy circle_start[];
+extern const coordxy circle_data[];
+extern const coordxy circle_start[];
 
 
 /* Create a new light source.  Caller (and extern.h) doesn't need to know
@@ -138,7 +138,7 @@ do_light_sources(seenV **cs_rows)
 {
     coordxy x, y, min_x, max_x, max_y;
     int offset;
-    coordxy *limits;
+    const coordxy *limits;
     short at_hero_range = 0;
     light_source *ls;
     seenV *row;
diff --git a/sys/windows/consoletty.c b/sys/windows/consoletty.c
index 7fd624106..ec6c3b665 100644
--- a/sys/windows/consoletty.c
+++ b/sys/windows/consoletty.c
@@ -921,7 +921,7 @@ void buffer_write(cell_t * buffer, cell_t * cell, COORD pos)
  * Called after returning from ! or ^Z
  */
 void
-gettty()
+gettty(void)
 {
 #ifndef TEXTCOLOR
     int k;
@@ -963,7 +963,7 @@ settty(const char* s)
 
 /* called by init_nhwindows() and resume_nhwindows() */
 void
-setftty()
+setftty(void)
 {
     start_screen();
 }
@@ -985,7 +985,7 @@ tty_number_pad(int state)
 }
 
 void
-tty_start_screen()
+tty_start_screen(void)
 {
     if (iflags.num_pad)
         tty_number_pad(1); /* make keypad send digits */
@@ -1000,7 +1000,7 @@ tty_start_screen()
 }
 
 void
-tty_end_screen()
+tty_end_screen(void)
 {
     clear_screen();
     really_move_cursor();
@@ -1055,7 +1055,7 @@ consoletty_open(int mode)
 }
 
 void
-consoletty_exit()
+consoletty_exit(void)
 {
     /* go back to using the safe routines */
     safe_routines();
@@ -1086,13 +1086,13 @@ process_keystroke(
 }
 
 int
-consoletty_kbhit()
+consoletty_kbhit(void)
 {
     return keyboard_handling.pNHkbhit(console.hConIn, &ir);
 }
 
 int
-tgetch()
+tgetch(void)
 {
     int mod;
     coord cc;
@@ -1159,7 +1159,7 @@ static void set_console_cursor(int x, int y)
 }
 
 static void
-really_move_cursor()
+really_move_cursor(void)
 {
 #ifdef PORT_DEBUG
     char oldtitle[BUFSZ], newtitle[BUFSZ];
@@ -2025,7 +2025,7 @@ static int CALLBACK EnumFontCallback(
  * correctly, then it will change the font to a known good font.
  */
 void
-check_and_set_font()
+check_and_set_font(void)
 {
     if (!check_font_widths()) {
         raw_print("WARNING: glyphs too wide in console font."
@@ -2039,7 +2039,7 @@ check_and_set_font()
  */
 boolean
 #ifndef VIRTUAL_TERMINAL_SEQUENCES
-check_font_widths()
+check_font_widths(void)
 #else /* VIRTUAL_TERMINAL_SEQUENCES */
 check_font_widths(void)
 #endif /* VIRTUAL_TERMINAL_SEQUENCES */
diff --git a/sys/windows/windmain.c b/sys/windows/windmain.c
index d51ee3815..8d51c7abc 100644
--- a/sys/windows/windmain.c
+++ b/sys/windows/windmain.c
@@ -239,7 +239,7 @@ test_portable_config(
 
 static char portable_device_path[MAX_PATH];
 
-const char *get_portable_device()
+const char *get_portable_device(void)
 {
     return (const char *) portable_device_path;
 }
@@ -361,7 +361,7 @@ update_file(
 
 }
 
-void copy_sysconf_content()
+void copy_sysconf_content(void)
 {
     /* Using the SYSCONFPREFIX path, lock it so that it does not change */
     fqn_prefix_locked[SYSCONFPREFIX] = TRUE;
@@ -381,7 +381,7 @@ void copy_sysconf_content()
 
 }
 
-void copy_config_content()
+void copy_config_content(void)
 {
     /* Using the CONFIGPREFIX path, lock it so that it does not change */
     fqn_prefix_locked[CONFIGPREFIX] = TRUE;
@@ -397,7 +397,7 @@ void copy_config_content()
 }
 
 void
-copy_hack_content()
+copy_hack_content(void)
 {
     nhassert(fqn_prefix_locked[HACKPREFIX]);
 
@@ -988,7 +988,7 @@ fakeconsole(void)
 #endif
     return has_fakeconsole;
 }
-void freefakeconsole()
+void freefakeconsole(void)
 {
     if (has_fakeconsole) {
         FreeConsole();