diff --git a/include/decl.h b/include/decl.h
index fedb98663..d07cc3ef4 100644
--- a/include/decl.h
+++ b/include/decl.h
@@ -404,12 +404,6 @@ struct early_opt {
     boolean valallowed;
 };
 
-/* topline states */
-#define TOPLINE_EMPTY          0 /* empty */
-#define TOPLINE_NEED_MORE      1 /* non-empty, need --More-- */
-#define TOPLINE_NON_EMPTY      2 /* non-empty, no --More-- required */
-#define TOPLINE_SPECIAL_PROMPT 3 /* special prompt state */
-
 /* special key functions */
 enum nh_keyfunc {
     NHKF_ESC = 0,
diff --git a/include/extern.h b/include/extern.h
index 8463293d5..8ee9b9917 100644
--- a/include/extern.h
+++ b/include/extern.h
@@ -1931,6 +1931,7 @@ E void VDECL(verbalize, (const char *, ...)) PRINTF_F(1, 2);
 E void VDECL(raw_printf, (const char *, ...)) PRINTF_F(1, 2);
 E void VDECL(impossible, (const char *, ...)) PRINTF_F(1, 2);
 E void VDECL(config_error_add, (const char *, ...)) PRINTF_F(1, 2);
+E void FDECL(nhassert_failed, (const char *, int));
 
 /* ### polyself.c ### */
 
diff --git a/include/global.h b/include/global.h
index f493d8a3e..509ffacea 100644
--- a/include/global.h
+++ b/include/global.h
@@ -380,5 +380,10 @@ struct savefile_info {
 #define nhassert(e) ((void)0)
 #endif
 
+/* Supply nhassert macro if not supplied by port */
+#ifndef nhassert
+#define nhassert(expression) (void)((!!(expression)) || \
+        (nhassert_failed(__FILE__, __LINE__), 0))
+#endif
 
 #endif /* GLOBAL_H */
diff --git a/include/ntconf.h b/include/ntconf.h
index 033cfb5d2..84188f7a9 100644
--- a/include/ntconf.h
+++ b/include/ntconf.h
@@ -134,6 +134,8 @@ extern void NDECL(getlock);
 #ifndef HAS_STDINT_H
 #define HAS_STDINT_H    /* force include of stdint.h in integer.h */
 #endif
+/* Turn on some additional warnings */
+#pragma warning(3:4389)
 #endif /* _MSC_VER */
 
 /* The following is needed for prototypes of certain functions */
@@ -146,14 +148,6 @@ extern void NDECL(getlock);
 #define strncmpi(a, b, c) strnicmp(a, b, c)
 #endif
 
-#ifdef _MSC_VER
-/* Visual Studio defines this in their own headers, which we don't use */
-#ifndef snprintf
-#define snprintf _snprintf
-#pragma warning( \
-    disable : 4996) /* deprecation warning suggesting snprintf_s */
-#endif
-#endif
 
 #include <sys/types.h>
 #include <stdlib.h>
@@ -274,17 +268,17 @@ extern int FDECL(set_win32_option, (const char *, const char *));
 extern int FDECL(alternative_palette, (char *));
 #endif
 
-#ifdef NDEBUG
-#define nhassert(expression) ((void)0)
-#else
-extern void FDECL(nhassert_failed, (const char * exp, const char * file,
-                                    int line));
-
-#define nhassert(expression) (void)((!!(expression)) || \
-        (nhassert_failed(#expression, __FILE__, __LINE__), 0))
-#endif
-
 #define nethack_enter(argc, argv) nethack_enter_winnt()
 extern void FDECL(nethack_exit, (int)) NORETURN;
 extern boolean FDECL(file_exists, (const char *));
+
+/* Override the default version of nhassert.  The default version is unable
+ * to generate a string form of the expression due to the need to be
+ * compatible with compilers which do not support macro stringization (i.e.
+ * #x to turn x into its string form).
+ */
+extern void FDECL(nt_assert_failed, (const char *, const char *, int));
+#define nhassert(expression) (void)((!!(expression)) || \
+        (nt_assert_failed(#expression, __FILE__, __LINE__), 0))
+
 #endif /* NTCONF_H */
diff --git a/include/wintty.h b/include/wintty.h
index 6994fc93f..e6388ec0d 100644
--- a/include/wintty.h
+++ b/include/wintty.h
@@ -50,6 +50,12 @@ struct WinDesc {
 #define WIN_STOP 1        /* for NHW_MESSAGE; stops output */
 #define WIN_LOCKHISTORY 2 /* for NHW_MESSAGE; suppress history updates */
 
+/* topline states */
+#define TOPLINE_EMPTY          0 /* empty */
+#define TOPLINE_NEED_MORE      1 /* non-empty, need --More-- */
+#define TOPLINE_NON_EMPTY      2 /* non-empty, no --More-- required */
+#define TOPLINE_SPECIAL_PROMPT 3 /* special prompt state */
+
 /* descriptor for tty-based displays -- all the per-display data */
 struct DisplayDesc {
     short rows, cols; /* width and height of tty display */
diff --git a/src/allmain.c b/src/allmain.c
index eff7eaa51..ce9f0e6c5 100644
--- a/src/allmain.c
+++ b/src/allmain.c
@@ -881,7 +881,7 @@ enum earlyarg e_arg;
  *                    optimization so that display output
  *                    can be debugged without buffering.
  */
-void
+STATIC_OVL void
 debug_fields(opts)
 const char *opts;
 {
diff --git a/src/apply.c b/src/apply.c
index 1205a7499..79f259002 100644
--- a/src/apply.c
+++ b/src/apply.c
@@ -1595,7 +1595,7 @@ int x,y;
             && is_valid_jump_pos(x, y, g.jumping_is_magic, FALSE));
 }
 
-void
+STATIC_OVL void
 display_jump_positions(state)
 int state;
 {
@@ -2848,7 +2848,7 @@ static const char
     cant_reach[] = "can't reach that spot from here.";
 
 /* find pos of monster in range, if only one monster */
-boolean
+STATIC_OVL boolean
 find_poleable_mon(pos, min_range, max_range)
 coord *pos;
 int min_range, max_range;
@@ -2901,7 +2901,7 @@ int x, y;
             && distu(x, y) <= g.polearm_range_max);
 }
 
-void
+STATIC_OVL void
 display_polearm_positions(state)
 int state;
 {
diff --git a/src/botl.c b/src/botl.c
index c73d3037f..79601bbbe 100644
--- a/src/botl.c
+++ b/src/botl.c
@@ -520,7 +520,7 @@ STATIC_VAR struct istat_s initblstats[MAXBLSTATS] = {
  * without STATUS_HILITES.
  */
 
-void
+STATIC_OVL void
 bot_via_windowport()
 {
     char buf[BUFSZ];
@@ -2769,7 +2769,7 @@ status_hilite_linestr_gather()
 }
 
 
-char *
+STATIC_OVL char *
 status_hilite2str(hl)
 struct hilite_s *hl;
 {
diff --git a/src/cmd.c b/src/cmd.c
index 1aed1ea61..a78de13c8 100644
--- a/src/cmd.c
+++ b/src/cmd.c
@@ -2567,7 +2567,7 @@ int final;
 }
 
 /* attributes: intrinsics and the like, other non-obvious capabilities */
-void
+STATIC_OVL void
 attributes_enlightenment(unused_mode, final)
 int unused_mode UNUSED;
 int final;
diff --git a/src/display.c b/src/display.c
index 8da876c66..61c94a2d9 100644
--- a/src/display.c
+++ b/src/display.c
@@ -897,7 +897,7 @@ xchar x, y;
     }
 }
 
-int
+STATIC_OVL int
 tether_glyph(x, y)
 int x, y;
 {
diff --git a/src/hack.c b/src/hack.c
index 9c08be267..8bd90c8d1 100644
--- a/src/hack.c
+++ b/src/hack.c
@@ -1341,7 +1341,7 @@ domove()
         g.domove_attempting = 0L;
 }
 
-void
+STATIC_OVL void
 domove_core()
 {
     register struct monst *mtmp;
@@ -1939,7 +1939,7 @@ domove_core()
     }
 }
 
-void
+STATIC_OVL void
 maybe_smudge_engr(x1,y1,x2,y2)
 int x1, y1, x2, y2;
 {
diff --git a/src/isaac64.c b/src/isaac64.c
index 9ccb0db55..4d19335a3 100644
--- a/src/isaac64.c
+++ b/src/isaac64.c
@@ -19,7 +19,9 @@
 #define ISAAC64_MASK ((uint64_t)0xFFFFFFFFFFFFFFFFULL)
 
 #if (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L)
+#if !defined(HAS_INLINE)
 #define HAS_INLINE
+#endif
 #else
 # if (defined(__GNUC__) && __GNUC__ >= 2 && !defined(inline))
 # define inline __inline__
diff --git a/src/makemon.c b/src/makemon.c
index 4c867fc0d..726b671d3 100644
--- a/src/makemon.c
+++ b/src/makemon.c
@@ -1033,7 +1033,7 @@ newmextra()
     return mextra;
 }
 
-boolean
+STATIC_OVL boolean
 makemon_rnd_goodpos(mon, gpflags, cc)
 struct monst *mon;
 unsigned gpflags;
diff --git a/src/mkmaze.c b/src/mkmaze.c
index 5f09d1bb3..a866ad88e 100644
--- a/src/mkmaze.c
+++ b/src/mkmaze.c
@@ -613,7 +613,7 @@ fixup_special()
     g.num_lregions = 0;
 }
 
-void
+STATIC_OVL void
 check_ransacked(s)
 char *s;
 {
@@ -624,7 +624,7 @@ char *s;
 #define ORC_LEADER 1
 static const char *orcfruit[] = { "paddle cactus", "dwarven root" };
 
-void
+STATIC_OVL void
 migrate_orc(mtmp, mflags)
 struct monst *mtmp;
 unsigned long mflags;
@@ -689,7 +689,7 @@ struct monst *mtmp;
             add_to_minv(mtmp, otmp);
     }
 }
-void
+STATIC_OVL void
 migr_booty_item(otyp, gang)
 int otyp;
 const char *gang;
@@ -710,7 +710,7 @@ const char *gang;
     }
 }
 
-void
+STATIC_OVL void
 stolen_booty(VOID_ARGS)
 {
     char *gang, gang_name[BUFSZ];
diff --git a/src/mon.c b/src/mon.c
index d6e45b722..c65972a86 100644
--- a/src/mon.c
+++ b/src/mon.c
@@ -43,7 +43,7 @@ const char *warnings[] = {
 #endif /* 0 */
 
 
-void
+STATIC_OVL void
 sanity_check_single_mon(mtmp, chk_geno, msg)
 struct monst *mtmp;
 boolean chk_geno;
@@ -2733,7 +2733,7 @@ struct monst *mtmp;
     return;
 }
 
-void
+STATIC_OVL void
 deal_with_overcrowding(mtmp)
 struct monst *mtmp;
 {
diff --git a/src/objnam.c b/src/objnam.c
index 1991e8e00..6660d42f6 100644
--- a/src/objnam.c
+++ b/src/objnam.c
@@ -411,7 +411,7 @@ struct obj *obj;
     return xname_flags(obj, CXN_NORMAL);
 }
 
-char *
+STATIC_OVL char *
 xname_flags(obj, cxn_flags)
 register struct obj *obj;
 unsigned cxn_flags; /* bitmask of CXN_xxx values */
@@ -2570,7 +2570,7 @@ const char *oldstr;
     return bp;
 }
 
-boolean
+STATIC_OVL boolean
 badman(basestr, to_plural)
 const char *basestr;
 boolean to_plural;            /* true => makeplural, false => makesingular */
diff --git a/src/options.c b/src/options.c
index 9176d0f76..b62bc7e01 100644
--- a/src/options.c
+++ b/src/options.c
@@ -1589,7 +1589,7 @@ int typ;
     return (char *) 0;
 }
 
-int
+STATIC_OVL int
 query_msgtype()
 {
     winid tmpwin;
@@ -1783,7 +1783,7 @@ const char *errmsg;
     return retval;
 }
 
-boolean
+STATIC_OVL boolean
 add_menu_coloring_parsed(str, c, a)
 char *str;
 int c, a;
diff --git a/src/pager.c b/src/pager.c
index b4b693f78..c98dff5bb 100644
--- a/src/pager.c
+++ b/src/pager.c
@@ -1409,7 +1409,7 @@ static const char *suptext2[] = {
     (char *) 0,
 };
 
-void
+STATIC_OVL void
 do_supplemental_info(name, pm, without_asking)
 char *name;
 struct permonst *pm;
@@ -1885,61 +1885,61 @@ docontact(VOID_ARGS)
     destroy_nhwindow(cwin);
 }
 
-void
+STATIC_OVL void
 dispfile_help(VOID_ARGS)
 {
     display_file(HELP, TRUE);
 }
 
-void
+STATIC_OVL void
 dispfile_shelp(VOID_ARGS)
 {
     display_file(SHELP, TRUE);
 }
 
-void
+STATIC_OVL void
 dispfile_optionfile(VOID_ARGS)
 {
     display_file(OPTIONFILE, TRUE);
 }
 
-void
+STATIC_OVL void
 dispfile_license(VOID_ARGS)
 {
     display_file(LICENSE, TRUE);
 }
 
-void
+STATIC_OVL void
 dispfile_debughelp(VOID_ARGS)
 {
     display_file(DEBUGHELP, TRUE);
 }
 
-void
+STATIC_OVL void
 hmenu_doextversion(VOID_ARGS)
 {
     (void) doextversion();
 }
 
-void
+STATIC_OVL void
 hmenu_dohistory(VOID_ARGS)
 {
     (void) dohistory();
 }
 
-void
+STATIC_OVL void
 hmenu_dowhatis(VOID_ARGS)
 {
     (void) dowhatis();
 }
 
-void
+STATIC_OVL void
 hmenu_dowhatdoes(VOID_ARGS)
 {
     (void) dowhatdoes();
 }
 
-void
+STATIC_OVL void
 hmenu_doextlist(VOID_ARGS)
 {
     (void) doextlist();
diff --git a/src/pickup.c b/src/pickup.c
index 1af0c51e8..8ae5ca59c 100644
--- a/src/pickup.c
+++ b/src/pickup.c
@@ -1697,7 +1697,7 @@ int x, y;
     return FALSE;
 }
 
-int
+STATIC_OVL int
 do_loot_cont(cobjp, cindex, ccount)
 struct obj **cobjp;
 int cindex, ccount; /* index of this container (1..N), number of them (N) */
diff --git a/src/pline.c b/src/pline.c
index 6f3bfa537..99ddb17d2 100644
--- a/src/pline.c
+++ b/src/pline.c
@@ -572,4 +572,21 @@ VA_DECL(const char *, str)
 #endif
 }
 
+/* nhassert_failed is called when an nhassert's condition is false */
+void
+nhassert_failed(filepath, line)
+    const char * filepath;
+    int line;
+{
+    const char * filename;
+
+    /* attempt to get filename from path.  TODO: we really need a port provided
+     * function to return a filename from a path */
+    filename = strrchr(filepath, '/');
+    filename = (filename == NULL ? strrchr(filepath, '\\') : filename);
+    filename = (filename == NULL ? filepath : filename + 1);
+
+    impossible("nhassert failed in file '%s' at line %d", filename, line);
+}
+
 /*pline.c*/
diff --git a/src/questpgr.c b/src/questpgr.c
index 97e9b106d..e2cdc8314 100644
--- a/src/questpgr.c
+++ b/src/questpgr.c
@@ -569,7 +569,7 @@ int how;
         putmsghistory(out_line, FALSE);
 }
 
-boolean
+STATIC_OVL boolean
 skip_pager(common)
 boolean common;
 {
diff --git a/src/shk.c b/src/shk.c
index fdd078485..ab1672faa 100644
--- a/src/shk.c
+++ b/src/shk.c
@@ -2719,7 +2719,7 @@ boolean ininv, dummy, silent;
     }
 }
 
-void
+STATIC_OVL void
 append_honorific(buf)
 char *buf;
 {
diff --git a/src/teleport.c b/src/teleport.c
index d32fb0990..037be54fb 100644
--- a/src/teleport.c
+++ b/src/teleport.c
@@ -1140,10 +1140,10 @@ struct monst *mtmp;
            sent out of his room (caller might resort to goodpos() if
            we report failure here, so this isn't full prevention) */
         if (mtmp->isshk && inhishop(mtmp)) {
-            if (levl[x][y].roomno != ESHK(mtmp)->shoproom)
+            if (levl[x][y].roomno != (unsigned char) ESHK(mtmp)->shoproom)
                 return FALSE;
         } else if (mtmp->ispriest && inhistemple(mtmp)) {
-            if (levl[x][y].roomno != EPRI(mtmp)->shroom)
+            if (levl[x][y].roomno != (unsigned char) EPRI(mtmp)->shroom)
                 return FALSE;
         }
         /* current location is <xx,yy> */
diff --git a/sys/winnt/winnt.c b/sys/winnt/winnt.c
index e9041262d..8d513c59e 100644
--- a/sys/winnt/winnt.c
+++ b/sys/winnt/winnt.c
@@ -475,23 +475,6 @@ char *buf;
 }
 #endif /* RUNTIME_PORT_ID */
 
-/* nhassert_failed is called when an nhassert's condition is false */
-void nhassert_failed(const char * exp, const char * file, int line)
-{
-    char message[128];
-    _snprintf(message, sizeof(message),
-                "NHASSERT(%s) in '%s' at line %d\n", exp, file, line);
-
-    if (IsDebuggerPresent()) {
-        OutputDebugStringA(message);
-        DebugBreak();
-    }
-
-    // strip off the newline
-    message[strlen(message) - 1] = '\0';
-    error(message);
-}
-
 void
 nethack_exit(code)
 int code;
@@ -725,6 +708,23 @@ sys_random_seed(VOID_ARGS)
     }
     return ourseed;
 }
+
+/* nt_assert_failed is called when an nhassert's condition is false */
+void
+nt_assert_failed(expression, filepath, line)
+    const char * expression;
+    const char * filepath;
+    int line;
+{
+    const char * filename;
+
+    /* get file name from path */
+    filename = strrchr(filepath, '\\');
+    filename = (filename == NULL ? filepath : filename + 1);
+    impossible("nhassert(%s) failed in file '%s' at line %d",
+                expression, filename, line);
+}
+
 #endif /* WIN32 */
 
 /*winnt.c*/
diff --git a/util/makedefs.c b/util/makedefs.c
index fb5dce367..953fdddd1 100644
--- a/util/makedefs.c
+++ b/util/makedefs.c
@@ -938,7 +938,7 @@ unsigned long old_rumor_offset;
     return rumor_offset;
 }
 
-void
+static void
 do_rnd_access_file(fname)
 const char *fname;
 {
@@ -1403,7 +1403,7 @@ do_date()
     return;
 }
 
-boolean
+static boolean
 get_gitinfo(githash, gitbranch)
 char *githash, *gitbranch;
 {
diff --git a/win/tty/topl.c b/win/tty/topl.c
index 7294f8bfd..334900d5e 100644
--- a/win/tty/topl.c
+++ b/win/tty/topl.c
@@ -139,7 +139,7 @@ const char *str;
     putsyms(str);
     cl_end();
     ttyDisplay->toplin = TOPLINE_NEED_MORE;
-    if (ttyDisplay->cury && otoplin != 3)
+    if (ttyDisplay->cury && otoplin != TOPLINE_SPECIAL_PROMPT)
         more();
 }
 
@@ -204,12 +204,15 @@ more()
 {
     struct WinDesc *cw = wins[WIN_MESSAGE];
 
-    /* avoid recursion -- only happens from interrupts */
-    if (ttyDisplay->inmore++)
-        return;
     if (iflags.debug_fuzzer)
         return;
 
+    /* avoid recursion -- only happens from interrupts */
+    if (ttyDisplay->inmore)
+        return;
+
+    ttyDisplay->inmore++;
+
     if (ttyDisplay->toplin) {
         tty_curs(BASE_WINDOW, cw->curx + 1, cw->cury);
         if (cw->curx >= CO - 8)
@@ -256,7 +259,8 @@ register const char *bp;
         && cw->cury == 0
         && n0 + (int) strlen(g.toplines) + 3 < CO - 8 /* room for --More-- */
         && (notdied = strncmp(bp, "You die", 7)) != 0) {
-        Strcat(g.toplines, "  ");
+        nhassert((long) strlen(g.toplines) == cw->curx);
+        Strcat(toplines, "  ");
         Strcat(g.toplines, bp);
         cw->curx += 2;
         if (!(cw->flags & WIN_STOP))
@@ -309,6 +313,7 @@ char c;
         if (ttyDisplay->curx == 0 && ttyDisplay->cury > 0)
             tty_curs(BASE_WINDOW, CO, (int) ttyDisplay->cury - 1);
         backsp();
+        nhassert(ttyDisplay->curx > 0);
         ttyDisplay->curx--;
         cw->curx = ttyDisplay->curx;
         return;
@@ -686,6 +691,13 @@ boolean restoring_msghist;
     }
 
     if (msg) {
+        /* Caller is asking us to remember a top line that needed more.
+           Should we call more?  This can happen when the player has set
+           iflags.force_invmenu and they attempt to shoot with nothing in
+           the quiver. */
+        if (ttyDisplay && ttyDisplay->toplin == TOPLINE_NEED_MORE)
+            ttyDisplay->toplin = TOPLINE_NON_EMPTY;
+
         /* move most recent message to history, make this become most recent */
         remember_topl();
         Strcpy(g.toplines, msg);
@@ -693,6 +705,9 @@ boolean restoring_msghist;
         dumplogmsg(g.toplines);
 #endif
     } else if (snapshot_mesgs) {
+        nhassert(ttyDisplay == NULL ||
+                 ttyDisplay->toplin != TOPLINE_NEED_MORE);
+
         /* done putting arbitrary messages in; put the snapshot ones back */
         for (idx = 0; snapshot_mesgs[idx]; ++idx) {
             remember_topl();
diff --git a/win/tty/wintty.c b/win/tty/wintty.c
index e4f1649e2..fc4cb79eb 100644
--- a/win/tty/wintty.c
+++ b/win/tty/wintty.c
@@ -2319,7 +2319,7 @@ boolean blocking; /* with ttys, all windows are blocking */
             more();
             ttyDisplay->toplin = TOPLINE_NEED_MORE; /* more resets this */
             tty_clear_nhwindow(window);
-            /* nhassert(ttyDisplay->toplin == TOPLINE_EMPTY); */
+            nhassert(ttyDisplay->toplin == TOPLINE_EMPTY);
         } else
             ttyDisplay->toplin = TOPLINE_EMPTY;
         cw->curx = cw->cury = 0;
@@ -2407,7 +2407,7 @@ winid window;
     case NHW_MESSAGE:
         if (ttyDisplay->toplin != TOPLINE_EMPTY)
             tty_display_nhwindow(WIN_MESSAGE, TRUE);
-        /* nhassert(ttyDisplay->toplin == TOPLINE_EMPTY); */
+        nhassert(ttyDisplay->toplin == TOPLINE_EMPTY);
         /*FALLTHRU*/
     case NHW_STATUS:
     case NHW_BASE:
@@ -3162,7 +3162,7 @@ const char *mesg;
         more();
         ttyDisplay->toplin = TOPLINE_NEED_MORE; /* more resets this */
         tty_clear_nhwindow(WIN_MESSAGE);
-        /* nhassert(ttyDisplay->toplin == TOPLINE_EMPTY); */
+        nhassert(ttyDisplay->toplin == TOPLINE_EMPTY);
     }
     /* normally <ESC> means skip further messages, but in this case
        it means cancel the current prompt; any other messages should
@@ -4130,7 +4130,7 @@ boolean force_update;
  * must be updated because they need to change.
  * This is now done at an individual field case-by-case level.
  */
-boolean
+STATIC_OVL boolean
 check_fields(forcefields, sz)
 boolean forcefields;
 int sz[3];