diff --git a/src/ball.c b/src/ball.c
index d6ba11017..ebacb7e83 100644
--- a/src/ball.c
+++ b/src/ball.c
@@ -743,7 +743,7 @@ drag_ball(coordxy x, coordxy y, int *bc_control,
                     SKIP_TO_DRAG;
                 break;
             }
-	    FALLTHROUGH;
+            FALLTHROUGH;
         /* FALLTHRU */
         case 1:
         case 0:
diff --git a/src/mon.c b/src/mon.c
index 69d206065..a87241014 100644
--- a/src/mon.c
+++ b/src/mon.c
@@ -3075,7 +3075,7 @@ mondead(struct monst *mtmp)
                 (void) makemon(mtmp->data, stway->sx, stway->sy, NO_MM_FLAGS);
                 break;
             }
-	    FALLTHROUGH;
+            FALLTHROUGH;
             /* FALLTHRU */
         case 2: /* randomly */
             (void) makemon(mtmp->data, 0, 0, NO_MM_FLAGS);
diff --git a/src/objnam.c b/src/objnam.c
index 94315442a..14227bc5c 100644
--- a/src/objnam.c
+++ b/src/objnam.c
@@ -5113,7 +5113,7 @@ readobjnam(char *bp, struct obj *no_wish)
        for fake mail); 1: from bones or wishing; 2: written with marker */
     case SCR_MAIL:
         d.otmp->spe = 1;
-	break;
+        break;
 #endif
     /* splash of venom:  0: normal, and transitory; 1: wishing */
     case ACID_VENOM:
diff --git a/src/pray.c b/src/pray.c
index b77c4faae..47d853a11 100644
--- a/src/pray.c
+++ b/src/pray.c
@@ -404,7 +404,7 @@ fix_worst_trouble(int trouble)
     case TROUBLE_STARVING:
         /* temporarily lost strength recovery now handled by init_uhunger() */
         FALLTHROUGH;
-	/* FALLTHRU*/
+        /* FALLTHRU*/
     case TROUBLE_HUNGRY:
         Your("%s feels content.", body_part(STOMACH));
         init_uhunger();
@@ -747,8 +747,8 @@ angrygods(aligntyp resp_god)
             punish((struct obj *) 0);
             break;
         }
-	FALLTHROUGH;
-	/* FALLTHRU */
+        FALLTHROUGH;
+        /* FALLTHRU */
     case 4:
     case 5:
         gods_angry(resp_god);
diff --git a/src/questpgr.c b/src/questpgr.c
index 9f630e05a..707846e90 100644
--- a/src/questpgr.c
+++ b/src/questpgr.c
@@ -406,8 +406,8 @@ convert_line(char *in_line, char *out_line)
                 cc += strlen(gc.cvt_buf);
                 break;
             }
-	    FALLTHROUGH;
-	    /* FALLTHRU */
+            FALLTHROUGH;
+            /* FALLTHRU */
         default:
             *cc++ = *c;
             break;
diff --git a/src/uhitm.c b/src/uhitm.c
index 9aaa11332..6cc8af687 100644
--- a/src/uhitm.c
+++ b/src/uhitm.c
@@ -6020,8 +6020,8 @@ passive_obj(
             }
             break;
         }
-	FALLTHROUGH;
-	/* FALLTHRU */
+        FALLTHROUGH;
+        /* FALLTHRU */
     default:
         break;
     }
diff --git a/src/wizard.c b/src/wizard.c
index 8db22f060..ce064615c 100644
--- a/src/wizard.c
+++ b/src/wizard.c
@@ -285,7 +285,7 @@ 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;