diff --git a/src/channel.c b/src/channel.c
index 3d891e8..3fdd312 100644
--- a/src/channel.c
+++ b/src/channel.c
@@ -4166,8 +4166,8 @@
 
 	    // Move the item from the list and then change the type to
 	    // avoid the value being freed.
-	    *rettv = list->lv_last->li_tv;
-	    list->lv_last->li_tv.v_type = VAR_NUMBER;
+	    *rettv = list->lv_u.mat.lv_last->li_tv;
+	    list->lv_u.mat.lv_last->li_tv.v_type = VAR_NUMBER;
 	    free_tv(listtv);
 	}
     }
diff --git a/src/evalfunc.c b/src/evalfunc.c
index 9cdd65a..19f7294 100644
--- a/src/evalfunc.c
+++ b/src/evalfunc.c
@@ -4070,7 +4070,7 @@
 	    // Start at specified item.  Use the cached index that list_find()
 	    // sets, so that a negative number also works.
 	    item = list_find(l, (long)tv_get_number_chk(&argvars[2], &error));
-	    idx = l->lv_idx;
+	    idx = l->lv_u.mat.lv_idx;
 	    if (argvars[3].v_type != VAR_UNKNOWN)
 		ic = (int)tv_get_number_chk(&argvars[3], &error);
 	    if (error)
@@ -4678,7 +4678,7 @@
 	    li = list_find(l, start);
 	    if (li == NULL)
 		goto theend;
-	    idx = l->lv_idx;	// use the cached index
+	    idx = l->lv_u.mat.lv_idx;	// use the cached index
 	}
 	else
 	{
@@ -5330,9 +5330,9 @@
 	// works with ":for".  If used otherwise range_list_materialize() must
 	// be called.
 	list->lv_first = &range_list_item;
-	list->lv_start = start;
-	list->lv_end = end;
-	list->lv_stride = stride;
+	list->lv_u.nonmat.lv_start = start;
+	list->lv_u.nonmat.lv_end = end;
+	list->lv_u.nonmat.lv_stride = stride;
 	list->lv_len = (end - start) / stride + 1;
     }
 }
@@ -5345,15 +5345,15 @@
 {
     if (list->lv_first == &range_list_item)
     {
-	varnumber_T start = list->lv_start;
-	varnumber_T end = list->lv_end;
-	int	    stride = list->lv_stride;
+	varnumber_T start = list->lv_u.nonmat.lv_start;
+	varnumber_T end = list->lv_u.nonmat.lv_end;
+	int	    stride = list->lv_u.nonmat.lv_stride;
 	varnumber_T i;
 
 	list->lv_first = NULL;
-	list->lv_last = NULL;
+	list->lv_u.mat.lv_last = NULL;
 	list->lv_len = 0;
-	list->lv_idx_item = NULL;
+	list->lv_u.mat.lv_idx_item = NULL;
 	for (i = start; stride > 0 ? i <= end : i >= end; i += stride)
 	    if (list_append_number(list, (varnumber_T)i) == FAIL)
 		break;
diff --git a/src/evalvars.c b/src/evalvars.c
index cc4a70f..a576859 100644
--- a/src/evalvars.c
+++ b/src/evalvars.c
@@ -2128,7 +2128,7 @@
     {
 	if (list_append_string(l, (char_u *)argv[i], -1) == FAIL)
 	    getout(1);
-	l->lv_last->li_tv.v_lock = VAR_FIXED;
+	l->lv_u.mat.lv_last->li_tv.v_lock = VAR_FIXED;
     }
     set_vim_var_list(VV_ARGV, l);
 }
diff --git a/src/if_mzsch.c b/src/if_mzsch.c
index e31d0e1..0ee922d 100644
--- a/src/if_mzsch.c
+++ b/src/if_mzsch.c
@@ -3044,7 +3044,7 @@
 	    MZ_GC_VAR_IN_REG(0, obj);
 	    MZ_GC_REG();
 
-	    curr = list->lv_last;
+	    curr = list->lv_u.mat.lv_last;
 	    obj = vim_to_mzscheme_impl(&curr->li_tv, depth + 1, visited);
 	    result = scheme_make_pair(obj, scheme_null);
 	    MZ_GC_CHECK();
diff --git a/src/if_py_both.h b/src/if_py_both.h
index 3da87cc..c4d82e7 100644
--- a/src/if_py_both.h
+++ b/src/if_py_both.h
@@ -2628,7 +2628,7 @@
 	    if (li)
 		lastaddedli = li->li_prev;
 	    else
-		lastaddedli = l->lv_last;
+		lastaddedli = l->lv_u.mat.lv_last;
 	    numadded++;
 	}
 	clear_tv(&v);
diff --git a/src/list.c b/src/list.c
index d5d09f6..855a20d 100644
--- a/src/list.c
+++ b/src/list.c
@@ -126,7 +126,7 @@
 	    l->lv_len = count;
 	    l->lv_with_items = count;
 	    l->lv_first = li;
-	    l->lv_last = li + count - 1;
+	    l->lv_u.mat.lv_last = li + count - 1;
 	    for (i = 0; i < count; ++i)
 	    {
 		if (i == 0)
@@ -406,25 +406,25 @@
     range_list_materialize(l);
 
     // When there is a cached index may start search from there.
-    if (l->lv_idx_item != NULL)
+    if (l->lv_u.mat.lv_idx_item != NULL)
     {
-	if (n < l->lv_idx / 2)
+	if (n < l->lv_u.mat.lv_idx / 2)
 	{
 	    // closest to the start of the list
 	    item = l->lv_first;
 	    idx = 0;
 	}
-	else if (n > (l->lv_idx + l->lv_len) / 2)
+	else if (n > (l->lv_u.mat.lv_idx + l->lv_len) / 2)
 	{
 	    // closest to the end of the list
-	    item = l->lv_last;
+	    item = l->lv_u.mat.lv_last;
 	    idx = l->lv_len - 1;
 	}
 	else
 	{
 	    // closest to the cached index
-	    item = l->lv_idx_item;
-	    idx = l->lv_idx;
+	    item = l->lv_u.mat.lv_idx_item;
+	    idx = l->lv_u.mat.lv_idx;
 	}
     }
     else
@@ -438,7 +438,7 @@
 	else
 	{
 	    // closest to the end of the list
-	    item = l->lv_last;
+	    item = l->lv_u.mat.lv_last;
 	    idx = l->lv_len - 1;
 	}
     }
@@ -457,8 +457,8 @@
     }
 
     // cache the used index
-    l->lv_idx = idx;
-    l->lv_idx_item = item;
+    l->lv_u.mat.lv_idx = idx;
+    l->lv_u.mat.lv_idx_item = item;
 
     return item;
 }
@@ -491,7 +491,7 @@
 	    return -1L;
 	}
 
-	return l->lv_start + n * l->lv_stride;
+	return l->lv_u.nonmat.lv_start + n * l->lv_u.nonmat.lv_stride;
     }
 
     li = list_find(l, idx);
@@ -549,18 +549,18 @@
 list_append(list_T *l, listitem_T *item)
 {
     range_list_materialize(l);
-    if (l->lv_last == NULL)
+    if (l->lv_u.mat.lv_last == NULL)
     {
 	// empty list
 	l->lv_first = item;
-	l->lv_last = item;
+	l->lv_u.mat.lv_last = item;
 	item->li_prev = NULL;
     }
     else
     {
-	l->lv_last->li_next = item;
-	item->li_prev = l->lv_last;
-	l->lv_last = item;
+	l->lv_u.mat.lv_last->li_next = item;
+	item->li_prev = l->lv_u.mat.lv_last;
+	l->lv_u.mat.lv_last = item;
     }
     ++l->lv_len;
     item->li_next = NULL;
@@ -710,12 +710,12 @@
 	if (item->li_prev == NULL)
 	{
 	    l->lv_first = ni;
-	    ++l->lv_idx;
+	    ++l->lv_u.mat.lv_idx;
 	}
 	else
 	{
 	    item->li_prev->li_next = ni;
-	    l->lv_idx_item = NULL;
+	    l->lv_u.mat.lv_idx_item = NULL;
 	}
 	item->li_prev = ni;
 	++l->lv_len;
@@ -846,14 +846,14 @@
     }
 
     if (item2->li_next == NULL)
-	l->lv_last = item->li_prev;
+	l->lv_u.mat.lv_last = item->li_prev;
     else
 	item2->li_next->li_prev = item->li_prev;
     if (item->li_prev == NULL)
 	l->lv_first = item2->li_next;
     else
 	item->li_prev->li_next = item2->li_next;
-    l->lv_idx_item = NULL;
+    l->lv_u.mat.lv_idx_item = NULL;
 }
 
 /*
@@ -1149,7 +1149,7 @@
 
     memset(sl, 0, sizeof(staticList10_T));
     l->lv_first = &sl->sl_items[0];
-    l->lv_last = &sl->sl_items[9];
+    l->lv_u.mat.lv_last = &sl->sl_items[9];
     l->lv_refcount = DO_NOT_FREE_CNT;
     l->lv_lock = VAR_FIXED;
     sl->sl_list.lv_len = 10;
@@ -1280,7 +1280,7 @@
 		    {
 			l = rettv->vval.v_list;
 			l->lv_first = item;
-			l->lv_last = item2;
+			l->lv_u.mat.lv_last = item2;
 			item->li_prev = NULL;
 			item2->li_next = NULL;
 			l->lv_len = cnt;
@@ -1605,7 +1605,8 @@
 		if (!info.item_compare_func_err)
 		{
 		    // Clear the List and append the items in sorted order.
-		    l->lv_first = l->lv_last = l->lv_idx_item = NULL;
+		    l->lv_first = l->lv_u.mat.lv_last
+					      = l->lv_u.mat.lv_idx_item = NULL;
 		    l->lv_len = 0;
 		    for (i = 0; i < len; ++i)
 			list_append(l, ptrs[i].item);
@@ -1645,7 +1646,7 @@
 		    if (li->li_next != NULL)
 			li->li_next->li_prev = ptrs[i].item;
 		    else
-			l->lv_last = ptrs[i].item;
+			l->lv_u.mat.lv_last = ptrs[i].item;
 		    list_fix_watch(l, li);
 		    listitem_free(l, li);
 		    l->lv_len--;
@@ -2259,16 +2260,17 @@
     {
 	if (l->lv_first == &range_list_item)
 	{
-	    varnumber_T new_start = l->lv_start
-					      + (l->lv_len - 1) * l->lv_stride;
-	    l->lv_end = new_start - (l->lv_end - l->lv_start);
-	    l->lv_start = new_start;
-	    l->lv_stride = -l->lv_stride;
+	    varnumber_T new_start = l->lv_u.nonmat.lv_start
+				  + (l->lv_len - 1) * l->lv_u.nonmat.lv_stride;
+	    l->lv_u.nonmat.lv_end = new_start
+			   - (l->lv_u.nonmat.lv_end - l->lv_u.nonmat.lv_start);
+	    l->lv_u.nonmat.lv_start = new_start;
+	    l->lv_u.nonmat.lv_stride = -l->lv_u.nonmat.lv_stride;
 	    rettv_list_set(rettv, l);
 	    return;
 	}
-	li = l->lv_last;
-	l->lv_first = l->lv_last = NULL;
+	li = l->lv_u.mat.lv_last;
+	l->lv_first = l->lv_u.mat.lv_last = NULL;
 	l->lv_len = 0;
 	while (li != NULL)
 	{
@@ -2277,7 +2279,7 @@
 	    li = ni;
 	}
 	rettv_list_set(rettv, l);
-	l->lv_idx = l->lv_len - l->lv_idx - 1;
+	l->lv_u.mat.lv_idx = l->lv_len - l->lv_u.mat.lv_idx - 1;
     }
 }
 
diff --git a/src/structs.h b/src/structs.h
index 74bc2ff..762cd86 100644
--- a/src/structs.h
+++ b/src/structs.h
@@ -1410,13 +1410,13 @@
 	    varnumber_T lv_start;
 	    varnumber_T lv_end;
 	    int		lv_stride;
-	};
+	} nonmat;
 	struct {	// used for materialized list
 	    listitem_T	*lv_last;	// last item, NULL if none
 	    listitem_T	*lv_idx_item;	// when not NULL item at index "lv_idx"
 	    int		lv_idx;		// cached index of an item
-	};
-    };
+	} mat;
+    } lv_u;
     list_T	*lv_copylist;	// copied list used by deepcopy()
     list_T	*lv_used_next;	// next list in used lists list
     list_T	*lv_used_prev;	// previous list in used lists list
diff --git a/src/version.c b/src/version.c
index 936f9b5..33fe21c 100644
--- a/src/version.c
+++ b/src/version.c
@@ -743,6 +743,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    173,
+/**/
     172,
 /**/
     171,
diff --git a/src/vim9compile.c b/src/vim9compile.c
index 524bcde..772355a 100644
--- a/src/vim9compile.c
+++ b/src/vim9compile.c
@@ -88,7 +88,7 @@
 	whilescope_T	se_while;
 	forscope_T	se_for;
 	tryscope_T	se_try;
-    };
+    } se_u;
 };
 
 /*
@@ -3506,7 +3506,7 @@
 	return NULL;
 
     // "where" is set when ":elseif", "else" or ":endif" is found
-    scope->se_if.is_if_label = instr->ga_len;
+    scope->se_u.se_if.is_if_label = instr->ga_len;
     generate_JUMP(cctx, JUMP_IF_FALSE, 0);
 
     return p;
@@ -3528,12 +3528,12 @@
     cctx->ctx_locals.ga_len = scope->se_local_count;
 
     // jump from previous block to the end
-    if (compile_jump_to_end(&scope->se_if.is_end_label,
+    if (compile_jump_to_end(&scope->se_u.se_if.is_end_label,
 						    JUMP_ALWAYS, cctx) == FAIL)
 	return NULL;
 
     // previous "if" or "elseif" jumps here
-    isn = ((isn_T *)instr->ga_data) + scope->se_if.is_if_label;
+    isn = ((isn_T *)instr->ga_data) + scope->se_u.se_if.is_if_label;
     isn->isn_arg.jump.jump_where = instr->ga_len;
 
     // compile "expr"
@@ -3541,7 +3541,7 @@
 	return NULL;
 
     // "where" is set when ":elseif", "else" or ":endif" is found
-    scope->se_if.is_if_label = instr->ga_len;
+    scope->se_u.se_if.is_if_label = instr->ga_len;
     generate_JUMP(cctx, JUMP_IF_FALSE, 0);
 
     return p;
@@ -3563,12 +3563,12 @@
     cctx->ctx_locals.ga_len = scope->se_local_count;
 
     // jump from previous block to the end
-    if (compile_jump_to_end(&scope->se_if.is_end_label,
+    if (compile_jump_to_end(&scope->se_u.se_if.is_end_label,
 						    JUMP_ALWAYS, cctx) == FAIL)
 	return NULL;
 
     // previous "if" or "elseif" jumps here
-    isn = ((isn_T *)instr->ga_data) + scope->se_if.is_if_label;
+    isn = ((isn_T *)instr->ga_data) + scope->se_u.se_if.is_if_label;
     isn->isn_arg.jump.jump_where = instr->ga_len;
 
     return p;
@@ -3587,12 +3587,12 @@
 	emsg(_(e_endif_without_if));
 	return NULL;
     }
-    ifscope = &scope->se_if;
+    ifscope = &scope->se_u.se_if;
     cctx->ctx_scope = scope->se_outer;
     cctx->ctx_locals.ga_len = scope->se_local_count;
 
     // previous "if" or "elseif" jumps here
-    isn = ((isn_T *)instr->ga_data) + scope->se_if.is_if_label;
+    isn = ((isn_T *)instr->ga_data) + scope->se_u.se_if.is_if_label;
     isn->isn_arg.jump.jump_where = instr->ga_len;
 
     // Fill in the "end" label in jumps at the end of the blocks.
@@ -3688,7 +3688,7 @@
     }
 
     // "for_end" is set when ":endfor" is found
-    scope->se_for.fs_top_label = instr->ga_len;
+    scope->se_u.se_for.fs_top_label = instr->ga_len;
 
     generate_FOR(cctx, loop_idx);
     generate_STORE(cctx, ISN_STORE, var_idx, NULL);
@@ -3712,7 +3712,7 @@
 	emsg(_(e_for));
 	return NULL;
     }
-    forscope = &scope->se_for;
+    forscope = &scope->se_u.se_for;
     cctx->ctx_scope = scope->se_outer;
     cctx->ctx_locals.ga_len = scope->se_local_count;
 
@@ -3757,14 +3757,14 @@
     if (scope == NULL)
 	return NULL;
 
-    scope->se_while.ws_top_label = instr->ga_len;
+    scope->se_u.se_while.ws_top_label = instr->ga_len;
 
     // compile "expr"
     if (compile_expr1(&p, cctx) == FAIL)
 	return NULL;
 
     // "while_end" is set when ":endwhile" is found
-    if (compile_jump_to_end(&scope->se_while.ws_end_label,
+    if (compile_jump_to_end(&scope->se_u.se_while.ws_end_label,
 						  JUMP_IF_FALSE, cctx) == FAIL)
 	return FAIL;
 
@@ -3788,11 +3788,11 @@
     cctx->ctx_locals.ga_len = scope->se_local_count;
 
     // At end of ":for" scope jump back to the FOR instruction.
-    generate_JUMP(cctx, JUMP_ALWAYS, scope->se_while.ws_top_label);
+    generate_JUMP(cctx, JUMP_ALWAYS, scope->se_u.se_while.ws_top_label);
 
     // Fill in the "end" label in the WHILE statement so it can jump here.
     // And in any jumps for ":break"
-    compile_fill_jump_to_end(&scope->se_while.ws_end_label, cctx);
+    compile_fill_jump_to_end(&scope->se_u.se_while.ws_end_label, cctx);
 
     vim_free(scope);
 
@@ -3821,8 +3821,8 @@
 
     // Jump back to the FOR or WHILE instruction.
     generate_JUMP(cctx, JUMP_ALWAYS,
-	    scope->se_type == FOR_SCOPE ? scope->se_for.fs_top_label
-					       : scope->se_while.ws_top_label);
+	    scope->se_type == FOR_SCOPE ? scope->se_u.se_for.fs_top_label
+					  : scope->se_u.se_while.ws_top_label);
     return arg;
 }
 
@@ -3849,9 +3849,9 @@
 
     // Jump to the end of the FOR or WHILE loop.
     if (scope->se_type == FOR_SCOPE)
-	el = &scope->se_for.fs_end_label;
+	el = &scope->se_u.se_for.fs_end_label;
     else
-	el = &scope->se_while.ws_end_label;
+	el = &scope->se_u.se_while.ws_end_label;
     if (compile_jump_to_end(el, JUMP_ALWAYS, cctx) == FAIL)
 	return FAIL;
 
@@ -3928,7 +3928,7 @@
 
     // "catch" is set when the first ":catch" is found.
     // "finally" is set when ":finally" or ":endtry" is found
-    try_scope->se_try.ts_try_label = instr->ga_len;
+    try_scope->se_u.se_try.ts_try_label = instr->ga_len;
     if (generate_instr(cctx, ISN_TRY) == NULL)
 	return NULL;
 
@@ -3963,33 +3963,33 @@
 	return NULL;
     }
 
-    if (scope->se_try.ts_caught_all)
+    if (scope->se_u.se_try.ts_caught_all)
     {
 	emsg(_("E1033: catch unreachable after catch-all"));
 	return NULL;
     }
 
     // Jump from end of previous block to :finally or :endtry
-    if (compile_jump_to_end(&scope->se_try.ts_end_label,
+    if (compile_jump_to_end(&scope->se_u.se_try.ts_end_label,
 						    JUMP_ALWAYS, cctx) == FAIL)
 	return NULL;
 
     // End :try or :catch scope: set value in ISN_TRY instruction
-    isn = ((isn_T *)instr->ga_data) + scope->se_try.ts_try_label;
+    isn = ((isn_T *)instr->ga_data) + scope->se_u.se_try.ts_try_label;
     if (isn->isn_arg.try.try_catch == 0)
 	isn->isn_arg.try.try_catch = instr->ga_len;
-    if (scope->se_try.ts_catch_label != 0)
+    if (scope->se_u.se_try.ts_catch_label != 0)
     {
 	// Previous catch without match jumps here
-	isn = ((isn_T *)instr->ga_data) + scope->se_try.ts_catch_label;
+	isn = ((isn_T *)instr->ga_data) + scope->se_u.se_try.ts_catch_label;
 	isn->isn_arg.jump.jump_where = instr->ga_len;
     }
 
     p = skipwhite(arg);
     if (ends_excmd(*p))
     {
-	scope->se_try.ts_caught_all = TRUE;
-	scope->se_try.ts_catch_label = 0;
+	scope->se_u.se_try.ts_caught_all = TRUE;
+	scope->se_u.se_try.ts_catch_label = 0;
     }
     else
     {
@@ -4003,7 +4003,7 @@
 	if (generate_COMPARE(cctx, EXPR_MATCH, FALSE) == FAIL)
 	    return NULL;
 
-	scope->se_try.ts_catch_label = instr->ga_len;
+	scope->se_u.se_try.ts_catch_label = instr->ga_len;
 	if (generate_JUMP(cctx, JUMP_IF_FALSE, 0) == FAIL)
 	    return NULL;
     }
@@ -4036,7 +4036,7 @@
     }
 
     // End :catch or :finally scope: set value in ISN_TRY instruction
-    isn = ((isn_T *)instr->ga_data) + scope->se_try.ts_try_label;
+    isn = ((isn_T *)instr->ga_data) + scope->se_u.se_try.ts_try_label;
     if (isn->isn_arg.try.try_finally != 0)
     {
 	emsg(_(e_finally_dup));
@@ -4044,12 +4044,12 @@
     }
 
     // Fill in the "end" label in jumps at the end of the blocks.
-    compile_fill_jump_to_end(&scope->se_try.ts_end_label, cctx);
+    compile_fill_jump_to_end(&scope->se_u.se_try.ts_end_label, cctx);
 
-    if (scope->se_try.ts_catch_label != 0)
+    if (scope->se_u.se_try.ts_catch_label != 0)
     {
 	// Previous catch without match jumps here
-	isn = ((isn_T *)instr->ga_data) + scope->se_try.ts_catch_label;
+	isn = ((isn_T *)instr->ga_data) + scope->se_u.se_try.ts_catch_label;
 	isn->isn_arg.jump.jump_where = instr->ga_len;
     }
 
@@ -4085,7 +4085,7 @@
 	return NULL;
     }
 
-    isn = ((isn_T *)instr->ga_data) + scope->se_try.ts_try_label;
+    isn = ((isn_T *)instr->ga_data) + scope->se_u.se_try.ts_try_label;
     if (isn->isn_arg.try.try_catch == 0 && isn->isn_arg.try.try_finally == 0)
     {
 	emsg(_("E1032: missing :catch or :finally"));
@@ -4094,7 +4094,7 @@
 
     // Fill in the "end" label in jumps at the end of the blocks, if not done
     // by ":finally".
-    compile_fill_jump_to_end(&scope->se_try.ts_end_label, cctx);
+    compile_fill_jump_to_end(&scope->se_u.se_try.ts_end_label, cctx);
 
     // End :catch or :finally scope: set value in ISN_TRY instruction
     if (isn->isn_arg.try.try_finally == 0)