diff --git a/dynasm/dasm_arm.h b/dynasm/dasm_arm.h
index a43f7c66..1d404ccd 100644
--- a/dynasm/dasm_arm.h
+++ b/dynasm/dasm_arm.h
@@ -254,6 +254,7 @@ void dasm_put(Dst_DECL, int start, ...)
       case DASM_IMMV8:
 	CK((n & 3) == 0, RANGE_I);
 	n >>= 2;
+	/* fallthrough */
       case DASM_IMML8:
       case DASM_IMML12:
 	CK(n >= 0 ? ((n>>((ins>>5)&31)) == 0) :
@@ -371,6 +372,7 @@ int dasm_encode(Dst_DECL, void *buffer)
 	  break;
 	case DASM_REL_LG:
 	  CK(n >= 0, UNDEF_LG);
+	  /* fallthrough */
 	case DASM_REL_PC:
 	  CK(n >= 0, UNDEF_PC);
 	  n = *DASM_POS2PTR(D, n) - (int)((char *)cp - base) - 4;
diff --git a/dynasm/dasm_mips.h b/dynasm/dasm_mips.h
index 4b49fd8c..71a835b2 100644
--- a/dynasm/dasm_mips.h
+++ b/dynasm/dasm_mips.h
@@ -350,6 +350,7 @@ int dasm_encode(Dst_DECL, void *buffer)
 	  break;
 	case DASM_REL_LG:
 	  CK(n >= 0, UNDEF_LG);
+	  /* fallthrough */
 	case DASM_REL_PC:
 	  CK(n >= 0, UNDEF_PC);
 	  n = *DASM_POS2PTR(D, n);
diff --git a/dynasm/dasm_ppc.h b/dynasm/dasm_ppc.h
index 3a7ee9b0..83fc030a 100644
--- a/dynasm/dasm_ppc.h
+++ b/dynasm/dasm_ppc.h
@@ -354,6 +354,7 @@ int dasm_encode(Dst_DECL, void *buffer)
 	  break;
 	case DASM_REL_LG:
 	  CK(n >= 0, UNDEF_LG);
+	  /* fallthrough */
 	case DASM_REL_PC:
 	  CK(n >= 0, UNDEF_PC);
 	  n = *DASM_POS2PTR(D, n) - (int)((char *)cp - base);
diff --git a/dynasm/dasm_x86.h b/dynasm/dasm_x86.h
index f598da9a..dc14d883 100644
--- a/dynasm/dasm_x86.h
+++ b/dynasm/dasm_x86.h
@@ -194,12 +194,13 @@ void dasm_put(Dst_DECL, int start, ...)
       switch (action) {
       case DASM_DISP:
 	if (n == 0) { if (mrm < 0) mrm = p[-2]; if ((mrm&7) != 5) break; }
-      case DASM_IMM_DB: if (((n+128)&-256) == 0) goto ob;
+	/* fallthrough */
+      case DASM_IMM_DB: if (((n+128)&-256) == 0) goto ob; /* fallthrough */
       case DASM_REL_A: /* Assumes ptrdiff_t is int. !x64 */
       case DASM_IMM_D: ofs += 4; break;
       case DASM_IMM_S: CK(((n+128)&-256) == 0, RANGE_I); goto ob;
       case DASM_IMM_B: CK((n&-256) == 0, RANGE_I); ob: ofs++; break;
-      case DASM_IMM_WB: if (((n+128)&-256) == 0) goto ob;
+      case DASM_IMM_WB: if (((n+128)&-256) == 0) goto ob; /* fallthrough */
       case DASM_IMM_W: CK((n&-65536) == 0, RANGE_I); ofs += 2; break;
       case DASM_SPACE: p++; ofs += n; break;
       case DASM_SETLABEL: b[pos-2] = -0x40000000; break;  /* Neg. label ofs. */
@@ -207,8 +208,8 @@ void dasm_put(Dst_DECL, int start, ...)
 	if (*p < 0x40 && p[1] == DASM_DISP) mrm = n;
 	if (*p < 0x20 && (n&7) == 4) ofs++;
 	switch ((*p++ >> 3) & 3) {
-	case 3: n |= b[pos-3];
-	case 2: n |= b[pos-2];
+	case 3: n |= b[pos-3]; /* fallthrough */
+	case 2: n |= b[pos-2]; /* fallthrough */
 	case 1: if (n <= 7) { b[pos-1] |= 0x10; ofs--; }
 	}
 	continue;
@@ -329,11 +330,14 @@ int dasm_link(Dst_DECL, size_t *szp)
 	  pos += 2;
 	  break;
 	}
+	  /* fallthrough */
 	case DASM_SPACE: case DASM_IMM_LG: case DASM_VREG: p++;
+	  /* fallthrough */
 	case DASM_DISP: case DASM_IMM_S: case DASM_IMM_B: case DASM_IMM_W:
 	case DASM_IMM_D: case DASM_IMM_WB: case DASM_IMM_DB:
 	case DASM_SETLABEL: case DASM_REL_A: case DASM_IMM_PC: pos++; break;
 	case DASM_LABEL_LG: p++;
+	  /* fallthrough */
 	case DASM_LABEL_PC: b[pos++] += ofs; break; /* Fix label offset. */
 	case DASM_ALIGN: ofs -= (b[pos++]+ofs)&*p++; break; /* Adjust ofs. */
 	case DASM_EXTERN: p += 2; break;
@@ -391,12 +395,15 @@ int dasm_encode(Dst_DECL, void *buffer)
 	    if (mrm != 5) { mm[-1] -= 0x80; break; } }
 	  if (((n+128) & -256) != 0) goto wd; else mm[-1] -= 0x40;
 	}
+	  /* fallthrough */
 	case DASM_IMM_S: case DASM_IMM_B: wb: dasmb(n); break;
 	case DASM_IMM_DB: if (((n+128)&-256) == 0) {
 	    db: if (!mark) mark = cp; mark[-2] += 2; mark = NULL; goto wb;
 	  } else mark = NULL;
+	  /* fallthrough */
 	case DASM_IMM_D: wd: dasmd(n); break;
 	case DASM_IMM_WB: if (((n+128)&-256) == 0) goto db; else mark = NULL;
+	  /* fallthrough */
 	case DASM_IMM_W: dasmw(n); break;
 	case DASM_VREG: {
 	  int t = *p++;
@@ -421,6 +428,7 @@ int dasm_encode(Dst_DECL, void *buffer)
 	}
 	case DASM_REL_LG: p++; if (n >= 0) goto rel_pc;
 	  b++; n = (int)(ptrdiff_t)D->globals[-n];
+	  /* fallthrough */
 	case DASM_REL_A: rel_a:
 	  n -= (unsigned int)(ptrdiff_t)(cp+4); goto wd; /* !x64 */
 	case DASM_REL_PC: rel_pc: {
@@ -433,6 +441,7 @@ int dasm_encode(Dst_DECL, void *buffer)
 	}
 	case DASM_IMM_LG:
 	  p++; if (n < 0) { n = (int)(ptrdiff_t)D->globals[-n]; goto wd; }
+	  /* fallthrough */
 	case DASM_IMM_PC: {
 	  int *pb = DASM_POS2PTR(D, n);
 	  n = *pb < 0 ? pb[1] : (*pb + (int)(ptrdiff_t)base);
@@ -453,6 +462,7 @@ int dasm_encode(Dst_DECL, void *buffer)
 	case DASM_EXTERN: n = DASM_EXTERN(Dst, cp, p[1], *p); p += 2; goto wd;
 	case DASM_MARK: mark = cp; break;
 	case DASM_ESC: action = *p++;
+	  /* fallthrough */
 	default: *cp++ = action; break;
 	case DASM_SECTION: case DASM_STOP: goto stop;
 	}
diff --git a/src/lj_asm.c b/src/lj_asm.c
index 5f83779e..992dcf59 100644
--- a/src/lj_asm.c
+++ b/src/lj_asm.c
@@ -2142,9 +2142,12 @@ static void asm_setup_regsp(ASMState *as)
 	if (ir->op2 != REF_NIL && as->evenspill < 4)
 	  as->evenspill = 4;  /* lj_cdata_newv needs 4 args. */
       }
+      /* fallthrough */
 #else
+      /* fallthrough */
     case IR_CNEW:
 #endif
+      /* fallthrough */
     case IR_TNEW: case IR_TDUP: case IR_CNEWI: case IR_TOSTR:
     case IR_BUFSTR:
       ir->prev = REGSP_HINT(RID_RET);
@@ -2165,6 +2168,7 @@ static void asm_setup_regsp(ASMState *as)
     case IR_LDEXP:
 #endif
 #endif
+      /* fallthrough */
     case IR_POW:
       if (!LJ_SOFTFP && irt_isnum(ir->t)) {
 	if (inloop)
@@ -2176,7 +2180,7 @@ static void asm_setup_regsp(ASMState *as)
 	continue;
 #endif
       }
-      /* fallthrough for integer POW */
+      /* fallthrough */ /* for integer POW */
     case IR_DIV: case IR_MOD:
       if (!irt_isnum(ir->t)) {
 	ir->prev = REGSP_HINT(RID_RET);
@@ -2213,6 +2217,7 @@ static void asm_setup_regsp(ASMState *as)
     case IR_BSHL: case IR_BSHR: case IR_BSAR:
       if ((as->flags & JIT_F_BMI2))  /* Except if BMI2 is available. */
 	break;
+      /* fallthrough */
     case IR_BROL: case IR_BROR:
       if (!irref_isk(ir->op2) && !ra_hashint(IR(ir->op2)->r)) {
 	IR(ir->op2)->r = REGSP_HINT(RID_ECX);
diff --git a/src/lj_cparse.c b/src/lj_cparse.c
index 83cfd112..19f632ff 100644
--- a/src/lj_cparse.c
+++ b/src/lj_cparse.c
@@ -576,28 +576,34 @@ static void cp_expr_infix(CPState *cp, CPValue *k, int pri)
 	k->id = k2.id > k3.id ? k2.id : k3.id;
 	continue;
       }
+      /* fallthrough */
     case 1:
       if (cp_opt(cp, CTOK_OROR)) {
 	cp_expr_sub(cp, &k2, 2); k->i32 = k->u32 || k2.u32; k->id = CTID_INT32;
 	continue;
       }
+      /* fallthrough */
     case 2:
       if (cp_opt(cp, CTOK_ANDAND)) {
 	cp_expr_sub(cp, &k2, 3); k->i32 = k->u32 && k2.u32; k->id = CTID_INT32;
 	continue;
       }
+      /* fallthrough */
     case 3:
       if (cp_opt(cp, '|')) {
 	cp_expr_sub(cp, &k2, 4); k->u32 = k->u32 | k2.u32; goto arith_result;
       }
+      /* fallthrough */
     case 4:
       if (cp_opt(cp, '^')) {
 	cp_expr_sub(cp, &k2, 5); k->u32 = k->u32 ^ k2.u32; goto arith_result;
       }
+      /* fallthrough */
     case 5:
       if (cp_opt(cp, '&')) {
 	cp_expr_sub(cp, &k2, 6); k->u32 = k->u32 & k2.u32; goto arith_result;
       }
+      /* fallthrough */
     case 6:
       if (cp_opt(cp, CTOK_EQ)) {
 	cp_expr_sub(cp, &k2, 7); k->i32 = k->u32 == k2.u32; k->id = CTID_INT32;
@@ -606,6 +612,7 @@ static void cp_expr_infix(CPState *cp, CPValue *k, int pri)
 	cp_expr_sub(cp, &k2, 7); k->i32 = k->u32 != k2.u32; k->id = CTID_INT32;
 	continue;
       }
+      /* fallthrough */
     case 7:
       if (cp_opt(cp, '<')) {
 	cp_expr_sub(cp, &k2, 8);
@@ -640,6 +647,7 @@ static void cp_expr_infix(CPState *cp, CPValue *k, int pri)
 	k->id = CTID_INT32;
 	continue;
       }
+      /* fallthrough */
     case 8:
       if (cp_opt(cp, CTOK_SHL)) {
 	cp_expr_sub(cp, &k2, 9); k->u32 = k->u32 << k2.u32;
@@ -652,6 +660,7 @@ static void cp_expr_infix(CPState *cp, CPValue *k, int pri)
 	  k->u32 = k->u32 >> k2.u32;
 	continue;
       }
+      /* fallthrough */
     case 9:
       if (cp_opt(cp, '+')) {
 	cp_expr_sub(cp, &k2, 10); k->u32 = k->u32 + k2.u32;
@@ -661,6 +670,7 @@ static void cp_expr_infix(CPState *cp, CPValue *k, int pri)
       } else if (cp_opt(cp, '-')) {
 	cp_expr_sub(cp, &k2, 10); k->u32 = k->u32 - k2.u32; goto arith_result;
       }
+      /* fallthrough */
     case 10:
       if (cp_opt(cp, '*')) {
 	cp_expr_unary(cp, &k2); k->u32 = k->u32 * k2.u32; goto arith_result;
diff --git a/src/lj_err.c b/src/lj_err.c
index b6be357e..abf176e5 100644
--- a/src/lj_err.c
+++ b/src/lj_err.c
@@ -150,6 +150,7 @@ static void *err_unwind(lua_State *L, void *stopcf, int errcode)
     case FRAME_CONT:  /* Continuation frame. */
       if (frame_iscont_fficb(frame))
 	goto unwind_c;
+      /* fallthrough */
     case FRAME_VARG:  /* Vararg frame. */
       frame = frame_prevd(frame);
       break;
diff --git a/src/lj_opt_sink.c b/src/lj_opt_sink.c
index a16d112f..c16363e7 100644
--- a/src/lj_opt_sink.c
+++ b/src/lj_opt_sink.c
@@ -100,8 +100,8 @@ static void sink_mark_ins(jit_State *J)
 	   (LJ_32 && ir+1 < irlast && (ir+1)->o == IR_HIOP &&
 	    !sink_checkphi(J, ir, (ir+1)->op2))))
 	irt_setmark(ir->t);  /* Mark ineligible allocation. */
-      /* fallthrough */
 #endif
+      /* fallthrough */
     case IR_USTORE:
       irt_setmark(IR(ir->op2)->t);  /* Mark stored value. */
       break;
diff --git a/src/lj_parse.c b/src/lj_parse.c
index 08f7cfa6..c8efafad 100644
--- a/src/lj_parse.c
+++ b/src/lj_parse.c
@@ -2667,7 +2667,8 @@ static int parse_stmt(LexState *ls)
       lj_lex_next(ls);
       parse_goto(ls);
       break;
-    }  /* else: fallthrough */
+    }
+    /* fallthrough */
   default:
     parse_call_assign(ls);
     break;
diff --git a/src/luajit.c b/src/luajit.c
index 1ca24301..3a3ec247 100644
--- a/src/luajit.c
+++ b/src/luajit.c
@@ -421,6 +421,7 @@ static int collectargs(char **argv, int *flags)
       break;
     case 'e':
       *flags |= FLAGS_EXEC;
+      /* fallthrough */
     case 'j':  /* LuaJIT extension */
     case 'l':
       *flags |= FLAGS_OPTION;