diff --git a/include/tradstdc.h b/include/tradstdc.h
index b607d4a99..8880c26f1 100644
--- a/include/tradstdc.h
+++ b/include/tradstdc.h
@@ -383,7 +383,7 @@ typedef genericptr genericptr_t; /* (void *) or (char *) */
 #define FALLTHROUGH __attribute__((fallthrough))
 #endif  /* __clang_major__ greater than or equal to 9 */
 #endif  /* __clang_major__ is defined */
-#endif  /* FALLTHROUGH */
+#endif  /*FALLTHRU*/
 #if !defined(DO_DEFINE_NONNULLS)
 #define DO_DEFINE_NONNULLS
 #endif
diff --git a/outdated/sys/wince/mhdlg.c b/outdated/sys/wince/mhdlg.c
index b56923222..1e15bd0b6 100644
--- a/outdated/sys/wince/mhdlg.c
+++ b/outdated/sys/wince/mhdlg.c
@@ -134,8 +134,7 @@ GetlinDlgProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
             SendDlgItemMessage(hWnd, IDC_GETLIN_EDIT, WM_GETTEXT,
                                (WPARAM) sizeof(wbuf), (LPARAM) wbuf);
             NH_W2A(wbuf, data->result, data->result_size);
-
-        /* Fall through. */
+            /*FALLTHRU*/
 
         /* cancel button was pressed */
         case IDCANCEL:
@@ -244,7 +243,7 @@ ExtCmdDlgProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
                 hWnd, IDC_EXTCMD_LIST, LB_GETCURSEL, (WPARAM) 0, (LPARAM) 0);
             if (*data->selection == LB_ERR)
                 *data->selection = -1;
-        /* Fall through. */
+            /*FALLTHRU*/
 
         /* CANCEL button ws clicked */
         case IDCANCEL:
diff --git a/outdated/win/gem/wingem.c b/outdated/win/gem/wingem.c
index df8d1d81c..7e438c5a0 100644
--- a/outdated/win/gem/wingem.c
+++ b/outdated/win/gem/wingem.c
@@ -711,7 +711,7 @@ const char *str;
 
     case NHW_MENU:
         mar_change_menu_2_text(window);
-    /* Fallthru */
+        /*FALLTHRU*/
     case NHW_TEXT:
         mar_putstr_text(window, attr, str);
         break;
diff --git a/src/apply.c b/src/apply.c
index e2e27e04d..5a077aee5 100644
--- a/src/apply.c
+++ b/src/apply.c
@@ -3199,7 +3199,7 @@ use_stone(struct obj *tstone)
             if (tstone->otyp == FLINT)
                 make_sparks = TRUE;
             FALLTHROUGH;
-            /* FALLTHRU */
+            /*FALLTHRU*/
         default:
             /* Objects passing the is_flimsy() test will not
                scratch a stone.  They will leave streaks on
@@ -4783,7 +4783,7 @@ doapply(void)
             return ECMD_OK;
         }
         FALLTHROUGH;
-        /* FALLTHRU */
+        /*FALLTHRU*/
     case CREDIT_CARD:
     case SKELETON_KEY:
         /* Lockpicking requires a free hand. */
@@ -4922,7 +4922,7 @@ doapply(void)
             break;
         }
         FALLTHROUGH;
-        /* FALLTHROUGH */
+        /*FALLTHRU*/
     case LUCKSTONE:
     case HEALTHSTONE:
     case LOADSTONE:
diff --git a/src/dothrow.c b/src/dothrow.c
index 6a4fd405e..6654c7fe1 100644
--- a/src/dothrow.c
+++ b/src/dothrow.c
@@ -2767,7 +2767,7 @@ breaktest(struct obj *obj)
         if (Role_if(PM_CARTOMANCER))
             return 0;
         FALLTHROUGH;
-        /* FALLTHRU */
+        /*FALLTHRU*/
     case POT_WATER: /* really, all potions */
     case CREAM_PIE:
     case MELON:
diff --git a/src/mhitm.c b/src/mhitm.c
index aad579571..35757a747 100644
--- a/src/mhitm.c
+++ b/src/mhitm.c
@@ -794,7 +794,8 @@ hitmm(
                                  weaphitmsg(mwep, magr));
                     break;
                 }
-                /* FALLTHRU */
+                FALLTHROUGH;
+                /*FALLTHRU*/
             case AT_CLAW: {
                 const char *verb = barehitmsg(magr);
                 Snprintf(buf, sizeof(buf), "%s %s", magr_name,
diff --git a/src/muse.c b/src/muse.c
index d72254079..326d83a38 100644
--- a/src/muse.c
+++ b/src/muse.c
@@ -2474,8 +2474,8 @@ rnd_offensive_item(struct monst *mtmp)
             || passes_walls(pm) || noncorporeal(pm) || unsolid(pm))
             return SCR_EARTH;
     }
-    FALLTHROUGH;
-    /* FALLTHRU */
+        FALLTHROUGH;
+        /*FALLTHRU*/
     case 1:
         return WAN_STRIKING;
     case 2:
diff --git a/src/pager.c b/src/pager.c
index 539ad8414..c80d23172 100644
--- a/src/pager.c
+++ b/src/pager.c
@@ -1635,7 +1635,8 @@ add_obj_info(winid datawin, struct obj *obj, short otyp, char *usr_text)
                         break;
                     case LIFESAVED:
                         effect = "life saving";
-                        /* FALLTHRU */
+                        FALLTHROUGH;
+                        /*FALLTHRU*/
                     /* for things that don't work with "Makes you" */
                     case GLIB:
                     case WOUNDED_LEGS:
diff --git a/src/pline.c b/src/pline.c
index 93d3a93c7..c97f21e89 100644
--- a/src/pline.c
+++ b/src/pline.c
@@ -277,7 +277,8 @@ vpline(const char *line, va_list the_args)
     switch (msgtyp) {
     case MSGTYP_ALERT:
         iflags.msg_is_alert = TRUE; /* <TAB> */
-        /* FALLTHRU */
+        FALLTHROUGH;
+        /*FALLTHRU*/
     case MSGTYP_STOP:
         display_nhwindow(WIN_MESSAGE, TRUE); /* --more-- */
         break;
diff --git a/src/potion.c b/src/potion.c
index d08cf80d1..d519c911e 100644
--- a/src/potion.c
+++ b/src/potion.c
@@ -2682,7 +2682,8 @@ potionbreathe(struct obj *obj)
         break;
     case POT_GAIN_LEVEL:
         more_experienced(5, 0);
-        /* FALLTHRU */
+        FALLTHROUGH;
+        /*FALLTHRU*/
     case POT_LEVITATION:
         You_feel("slightly elevated.");
         /* Strictly speaking, this is only unambiguous if the player has showexp
diff --git a/src/questpgr.c b/src/questpgr.c
index 707846e90..76ee1375e 100644
--- a/src/questpgr.c
+++ b/src/questpgr.c
@@ -407,7 +407,7 @@ convert_line(char *in_line, char *out_line)
                 break;
             }
             FALLTHROUGH;
-            /* FALLTHRU */
+            /*FALLTHRU*/
         default:
             *cc++ = *c;
             break;
diff --git a/src/rumors.c b/src/rumors.c
index 60850b559..96b6fb184 100644
--- a/src/rumors.c
+++ b/src/rumors.c
@@ -564,7 +564,7 @@ outrumor(
     case BY_COOKIE:
         pline(fortune_msg);
         FALLTHROUGH;
-    /* FALLTHRU */
+        /*FALLTHRU*/
     case BY_PAPER:
         pline("It reads:");
         break;
diff --git a/src/sounds.c b/src/sounds.c
index bfcc67567..a5fc91902 100644
--- a/src/sounds.c
+++ b/src/sounds.c
@@ -1253,8 +1253,8 @@ domonnoise(struct monst *mtmp)
             (void) demon_talk(mtmp);
             break;
         }
-	FALLTHROUGH;
-        /* FALLTHRU */
+	    FALLTHROUGH;
+        /*FALLTHRU*/
     case MS_CUSS:
         if (!mtmp->mpeaceful)
             cuss(mtmp);
diff --git a/src/trap.c b/src/trap.c
index bc2385b8d..2ff745b74 100644
--- a/src/trap.c
+++ b/src/trap.c
@@ -7227,7 +7227,7 @@ chest_trap(
             }
             /* No mon data was made, so just... */
         }
-        /* FALLTHROUGH*/
+        /*FALLTHRU*/
         case 3: {
             /* Cream pie in the face */
             struct obj pseudo;
diff --git a/src/uhitm.c b/src/uhitm.c
index d9dcefe84..d00df0bc0 100644
--- a/src/uhitm.c
+++ b/src/uhitm.c
@@ -7411,7 +7411,7 @@ passive_obj(
             break;
         }
         FALLTHROUGH;
-        /* FALLTHRU */
+        /*FALLTHRU*/
     default:
         break;
     }
@@ -7746,7 +7746,8 @@ bite_monster(struct monst *mon)
             You("don't feel very well.");
             Slimed = 10L;
         }
-        /* Fall through */
+        FALLTHROUGH;
+        /*FALLTHRU*/
     default:
         if (acidic(mon->data) && Stoned)
 	        fix_petrification();
diff --git a/src/weapon.c b/src/weapon.c
index 98cad2d24..89dcdfc89 100644
--- a/src/weapon.c
+++ b/src/weapon.c
@@ -1827,7 +1827,7 @@ weapon_hit_bonus(struct obj *weapon)
         default:
             impossible(bad_skill, P_SKILL(type));
             FALLTHROUGH;
-            /* FALLTHRU */
+            /*FALLTHRU*/
         case P_ISRESTRICTED:
         case P_UNSKILLED:
             bonus = -4;
@@ -1853,7 +1853,7 @@ weapon_hit_bonus(struct obj *weapon)
         default:
             impossible(bad_skill, skill);
             FALLTHROUGH;
-            /* FALLTHRU */
+            /*FALLTHRU*/
         case P_ISRESTRICTED:
         case P_UNSKILLED:
             bonus = -9;
@@ -1928,7 +1928,7 @@ weapon_dam_bonus(struct obj *weapon)
         default:
             impossible("weapon_dam_bonus: bad skill %d", P_SKILL(type));
             FALLTHROUGH;
-        /* FALLTHRU */
+            /*FALLTHRU*/
         case P_ISRESTRICTED:
         case P_UNSKILLED:
             bonus = -2;
diff --git a/src/wizard.c b/src/wizard.c
index 663599d86..d5a1c0bd2 100644
--- a/src/wizard.c
+++ b/src/wizard.c
@@ -287,7 +287,7 @@ strategy(struct monst *mtmp)
         if (mtmp->data != &mons[PM_WIZARD_OF_YENDOR])
             return (unsigned long) STRAT_HEAL;
         FALLTHROUGH;
-        /* FALLTHRU */
+        /*FALLTHRU*/
     case 2:
         dstrat = STRAT_HEAL;
         break;
diff --git a/src/zap.c b/src/zap.c
index 10e700b91..7494d6add 100644
--- a/src/zap.c
+++ b/src/zap.c
@@ -3177,7 +3177,7 @@ zapyourself(struct obj *obj, boolean ordinary)
         break;
     case WAN_DRAINING:	/* KMH */
         makeknown(obj->otyp);
-        /* FALLTHROUGH */
+        /*FALLTHRU*/
     case SPE_DRAIN_LIFE:
         if (!Drain_resistance) {
             learn_it = TRUE; /* (no effect for spells...) */
diff --git a/sys/share/pcmain.c b/sys/share/pcmain.c
index 57d04c5fa..9b5c4a8e4 100644
--- a/sys/share/pcmain.c
+++ b/sys/share/pcmain.c
@@ -625,7 +625,7 @@ process_options(int argc, char *argv[])
                 break;
             } else
                 raw_printf("\nUnknown switch: %s", argv[0]);
-        /* FALL THROUGH */
+        /*FALLTHRU*/
         case '?':
             nhusage();
             nethack_exit(EXIT_SUCCESS);
diff --git a/sys/windows/consoletty.c b/sys/windows/consoletty.c
index 35bedebba..8d49c9be1 100644
--- a/sys/windows/consoletty.c
+++ b/sys/windows/consoletty.c
@@ -1337,7 +1337,7 @@ xputc_core(int ch)
         if (console.cursor.Y < console.height - 1)
             console.cursor.Y++;
         FALLTHROUGH;
-    /* FALLTHRU */
+        /*FALLTHRU*/
     case '\r':
         console.cursor.X = 1;
         break;
diff --git a/sys/windows/windmain.c b/sys/windows/windmain.c
index 6bb686e67..691f04a99 100644
--- a/sys/windows/windmain.c
+++ b/sys/windows/windmain.c
@@ -637,7 +637,7 @@ process_options(int argc, char * argv[])
             } else
                 raw_printf("\nUnknown switch: %s", argv[0]);
         FALLTHROUGH;
-	/* FALLTHRU */
+	/*FALLTHRU*/
         case '?':
             nhusage();
             nethack_exit(EXIT_SUCCESS);
diff --git a/util/makedefs.c b/util/makedefs.c
index f09a2ceb1..16b260166 100644
--- a/util/makedefs.c
+++ b/util/makedefs.c
@@ -847,7 +847,7 @@ do_grep_control(char *buf)
     case '!': /* if not ID */
         isif = 0;
         FALLTHROUGH;
-    /* FALLTHRU */
+        /*FALLTHRU*/
     case '?': /* if ID */
         if (grep_sp == GREP_STACK_SIZE - 2) {
             Fprintf(stderr, "stack overflow at line %d.", grep_lineno);
diff --git a/win/win32/mhdlg.c b/win/win32/mhdlg.c
index f190f000d..55e24bff7 100644
--- a/win/win32/mhdlg.c
+++ b/win/win32/mhdlg.c
@@ -147,7 +147,7 @@ GetlinDlgProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
             NH_W2A(wbuf2, data->result, data->result_size);
 
         FALLTHROUGH;
-        /* FALLTHRU */
+        /*FALLTHRU*/
 
         /* cancel button was pressed */
         case IDCANCEL:
@@ -248,7 +248,7 @@ ExtCmdDlgProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
             if (*data->selection == LB_ERR)
                 *data->selection = -1;
             FALLTHROUGH;
-            /* FALLTHRU */
+            /*FALLTHRU*/
 
         /* CANCEL button ws clicked */
         case IDCANCEL: