diff --git a/data/strings/en.ini b/data/strings/en.ini
index 0f8e7d60b..226e24198 100644
--- a/data/strings/en.ini
+++ b/data/strings/en.ini
@@ -1023,9 +1023,11 @@ default_new_layer_name = New Layer
 new_tileset = New Tileset
 grid_width = Grid Width:
 grid_height = Grid Height:
-first_visible_index = First Visible Index:
-first_visible_index_tooltip = <<<END
-Change how you see the tile of index 1 (you can set it to 0 or any value).
+base_index = Base Index:
+base_tooltip = <<<END
+Visible aid to see the first tile with content from the tileset
+as index 1 (by default, one-based index) or other value.
+E.g. you can use 0 here for zero-based indexing.
 END
 
 [new_sprite]
diff --git a/data/widgets/tileset_selector.xml b/data/widgets/tileset_selector.xml
index 4daa0e342..6dcf03cb5 100644
--- a/data/widgets/tileset_selector.xml
+++ b/data/widgets/tileset_selector.xml
@@ -13,9 +13,9 @@
     <label text="@.grid_height" />
     <expr id="grid_height" text="" />
 
-    <label text="@.first_visible_index" />
-    <expr id="first_visible_index" text="1" tooltip="@.first_visible_index_tooltip" />
-    <booxfiller cell_hspan="2" />
+    <label text="@.base_index" />
+    <expr id="base_index" text="1" tooltip="@.base_tooltip" />
+    <boxfiller cell_hspan="2" />
   </grid>
 </vbox>
 </gui>
diff --git a/docs/ase-file-specs.md b/docs/ase-file-specs.md
index 7f2587602..d7e7ff1b5 100644
--- a/docs/ase-file-specs.md
+++ b/docs/ase-file-specs.md
@@ -374,9 +374,12 @@ the Tags chunk.
     DWORD       Number of tiles
     WORD        Tile Width
     WORD        Tile Height
-    SHORT       Number to show in the screen from the tile with index 1 and
-                so on (by default this is field is 1, so the data that is
-                displayed is equivalent to the data in memory)
+    SHORT       Base Index: Number to show in the screen from the tile with
+                index 1 and so on (by default this is field is 1, so the data
+                that is displayed is equivalent to the data in memory). But it
+                can be 0 to display zero-based indexing (this field isn't used
+                for the representation of the data in the file, it's just for
+                UI purposes).
     BYTE[14]    Reserved
     STRING      Name of the tileset
     + If flag 1 is set
diff --git a/src/app/commands/cmd_new_layer.cpp b/src/app/commands/cmd_new_layer.cpp
index fb06c7648..4c95ed01d 100644
--- a/src/app/commands/cmd_new_layer.cpp
+++ b/src/app/commands/cmd_new_layer.cpp
@@ -195,7 +195,7 @@ void NewLayerCommand::onExecute(Context* context)
   TilesetSelector::Info tilesetInfo;
   tilesetInfo.newTileset = true;
   tilesetInfo.grid = context->activeSite().grid();
-  tilesetInfo.firstVisibleIndex = 1;
+  tilesetInfo.baseIndex = 1;
 
 #ifdef ENABLE_UI
   // If params specify to ask the user about the name...
@@ -268,7 +268,7 @@ void NewLayerCommand::onExecute(Context* context)
         tileset_index tsi;
         if (tilesetInfo.newTileset) {
           auto tileset = new Tileset(sprite, tilesetInfo.grid, 1);
-          tileset->setFirstVisibleIndex(tilesetInfo.firstVisibleIndex);
+          tileset->setBaseIndex(tilesetInfo.baseIndex);
 
           auto addTileset = new cmd::AddTileset(sprite, tileset);
           tx(addTileset);
diff --git a/src/app/file/ase_format.cpp b/src/app/file/ase_format.cpp
index cf3a2a89e..7b4f280ff 100644
--- a/src/app/file/ase_format.cpp
+++ b/src/app/file/ase_format.cpp
@@ -1283,7 +1283,7 @@ static void ase_file_write_tileset_chunk(FILE* f, FileOp* fop,
   fputl(tileset->size(), f);
   fputw(tileset->grid().tileSize().w, f);
   fputw(tileset->grid().tileSize().h, f);
-  fputw(short(tileset->firstVisibleIndex()), f);
+  fputw(short(tileset->baseIndex()), f);
   ase_file_write_padding(f, 14);
   ase_file_write_string(f, tileset->name()); // tileset name
 
diff --git a/src/app/script/tileset_class.cpp b/src/app/script/tileset_class.cpp
index 8e2d5360d..bbbea84ff 100644
--- a/src/app/script/tileset_class.cpp
+++ b/src/app/script/tileset_class.cpp
@@ -69,18 +69,18 @@ int Tileset_get_grid(lua_State* L)
   return 1;
 }
 
-int Tileset_get_firstVisibleIndex(lua_State* L)
+int Tileset_get_baseIndex(lua_State* L)
 {
   auto tileset = get_docobj<Tileset>(L, 1);
-  lua_pushinteger(L, tileset->firstVisibleIndex());
+  lua_pushinteger(L, tileset->baseIndex());
   return 1;
 }
 
-int Tileset_set_firstVisibleIndex(lua_State* L)
+int Tileset_set_baseIndex(lua_State* L)
 {
   auto tileset = get_docobj<Tileset>(L, 1);
   int i = lua_tointeger(L, 2);
-  tileset->setFirstVisibleIndex(i);
+  tileset->setBaseIndex(i);
   return 0;
 }
 
@@ -96,7 +96,7 @@ const luaL_Reg Tileset_methods[] = {
 const Property Tileset_properties[] = {
   { "name", Tileset_get_name, Tileset_set_name },
   { "grid", Tileset_get_grid, nullptr },
-  { "firstVisibleIndex", Tileset_get_firstVisibleIndex, Tileset_set_firstVisibleIndex },
+  { "baseIndex", Tileset_get_baseIndex, Tileset_set_baseIndex },
   { nullptr, nullptr, nullptr }
 };
 
diff --git a/src/app/ui/editor/editor.cpp b/src/app/ui/editor/editor.cpp
index 68aacc2f6..cbdae8a81 100644
--- a/src/app/ui/editor/editor.cpp
+++ b/src/app/ui/editor/editor.cpp
@@ -1162,7 +1162,7 @@ void Editor::drawTileNumbers(ui::Graphics* g, const Cel* cel)
       + mainTilePosition();
 
     int ti_offset =
-      static_cast<LayerTilemap*>(cel->layer())->tileset()->firstVisibleIndex() - 1;
+      static_cast<LayerTilemap*>(cel->layer())->tileset()->baseIndex() - 1;
 
     const gfx::Rect rc = cel->bounds();
     const doc::Image* image = cel->image();
diff --git a/src/app/ui/status_bar.cpp b/src/app/ui/status_bar.cpp
index 14cad9497..239e1d057 100644
--- a/src/app/ui/status_bar.cpp
+++ b/src/app/ui/status_bar.cpp
@@ -472,17 +472,17 @@ public:
     }
     else {
       // TODO could the site came from the Indicators or StatusBar itself
-      int firstVisibleIndex = 1;
+      int baseIndex = 1;
       Site site = UIContext::instance()->activeSite();
       if (site.tileset())
-        firstVisibleIndex = site.tileset()->firstVisibleIndex();
+        baseIndex = site.tileset()->baseIndex();
 
       doc::tile_index ti = doc::tile_geti(tile);
       doc::tile_flags tf = doc::tile_getf(tile);
-      if (firstVisibleIndex < 0)
-        str += fmt::format("{}", ((int)ti) + firstVisibleIndex - 1);
+      if (baseIndex < 0)
+        str += fmt::format("{}", ((int)ti) + baseIndex - 1);
       else
-        str += fmt::format("{}", ti + firstVisibleIndex - 1);
+        str += fmt::format("{}", ti + baseIndex - 1);
       if (tf) {
         if (tf & doc::tile_f_flipx) str += " FlipX";
         if (tf & doc::tile_f_flipy) str += " FlipY";
diff --git a/src/app/ui/tile_button.cpp b/src/app/ui/tile_button.cpp
index 34325a74e..b4d2c3247 100644
--- a/src/app/ui/tile_button.cpp
+++ b/src/app/ui/tile_button.cpp
@@ -145,11 +145,11 @@ void TileButton::onPaint(PaintEvent& ev)
 
   // Draw text
   if (m_tile != doc::notile) {
-    int firstVisibleIndex = 1;
+    int baseIndex = 1;
     if (site.tileset())
-      firstVisibleIndex = site.tileset()->firstVisibleIndex();
+      baseIndex = site.tileset()->baseIndex();
 
-    std::string str = fmt::format("{}", doc::tile_geti(m_tile) + firstVisibleIndex - 1);
+    std::string str = fmt::format("{}", doc::tile_geti(m_tile) + baseIndex - 1);
     setTextQuiet(str.c_str());
 
     // TODO calc a proper color for the text
diff --git a/src/app/ui/tileset_selector.cpp b/src/app/ui/tileset_selector.cpp
index f6feb6a7a..afddf551f 100644
--- a/src/app/ui/tileset_selector.cpp
+++ b/src/app/ui/tileset_selector.cpp
@@ -27,7 +27,7 @@ TilesetSelector::TilesetSelector(const doc::Sprite* sprite,
 
   gridWidth()->setTextf("%d", info.grid.tileSize().w);
   gridHeight()->setTextf("%d", info.grid.tileSize().h);
-  firstVisibleIndex()->setTextf("%d", info.firstVisibleIndex);
+  baseIndex()->setTextf("%d", info.baseIndex);
 
   doc::tileset_index tsi = 0;
   for (doc::Tileset* tileset : *sprite->tilesets()) {
@@ -60,7 +60,7 @@ TilesetSelector::Info TilesetSelector::getInfo()
 
     info.newTileset = true;
     info.grid = doc::Grid::MakeRect(sz);
-    info.firstVisibleIndex = firstVisibleIndex()->textInt();
+    info.baseIndex = baseIndex()->textInt();
   }
   else {
     info.newTileset = false;
diff --git a/src/app/ui/tileset_selector.h b/src/app/ui/tileset_selector.h
index 15f0037ac..a8346f222 100644
--- a/src/app/ui/tileset_selector.h
+++ b/src/app/ui/tileset_selector.h
@@ -25,7 +25,7 @@ namespace app {
     struct Info {
       bool newTileset = true;
       doc::Grid grid;
-      int firstVisibleIndex = 1;
+      int baseIndex = 1;
       doc::tileset_index tsi = 0;
     };
 
diff --git a/src/dio/aseprite_decoder.cpp b/src/dio/aseprite_decoder.cpp
index 1270f2e6d..5337dc3fc 100644
--- a/src/dio/aseprite_decoder.cpp
+++ b/src/dio/aseprite_decoder.cpp
@@ -1068,7 +1068,7 @@ void AsepriteDecoder::readTilesetChunk(doc::Sprite* sprite,
   const doc::tile_index ntiles = read32();
   const int w = read16();
   const int h = read16();
-  const int firstVisibleIndex = short(read16());
+  const int baseIndex = short(read16());
   readPadding(14);
   const std::string name = readString();
 
@@ -1083,7 +1083,7 @@ void AsepriteDecoder::readTilesetChunk(doc::Sprite* sprite,
   doc::Grid grid(gfx::Size(w, h));
   auto tileset = new doc::Tileset(sprite, grid, ntiles);
   tileset->setName(name);
-  tileset->setFirstVisibleIndex(firstVisibleIndex);
+  tileset->setBaseIndex(baseIndex);
 
   if (flags & ASE_TILESET_FLAG_EXTERNAL_FILE) {
     const uint32_t extFileId = read32(); // filename ID in the external files chunk
diff --git a/src/doc/tileset.h b/src/doc/tileset.h
index 03cb015c9..f049de00b 100644
--- a/src/doc/tileset.h
+++ b/src/doc/tileset.h
@@ -45,8 +45,8 @@ namespace doc {
     const std::string& name() const { return m_name; }
     void setName(const std::string& name) { m_name = name; }
 
-    int firstVisibleIndex() const { return m_firstVisibleIndex; }
-    void setFirstVisibleIndex(int index) { m_firstVisibleIndex = index; }
+    int baseIndex() const { return m_baseIndex; }
+    void setBaseIndex(int index) { m_baseIndex = index; }
 
     int getMemSize() const override;
 
@@ -124,7 +124,7 @@ namespace doc {
     Tiles m_tiles;
     TilesetHashTable m_hash;
     std::string m_name;
-    int m_firstVisibleIndex = 1;
+    int m_baseIndex = 1;
     struct External {
       std::string filename;
       tileset_index tileset;
diff --git a/src/doc/tileset_io.cpp b/src/doc/tileset_io.cpp
index 3207448b9..488c5e602 100644
--- a/src/doc/tileset_io.cpp
+++ b/src/doc/tileset_io.cpp
@@ -71,7 +71,7 @@ Tileset* read_tileset(std::istream& is,
     if (isOldVersion)
       *isOldVersion = false;
 
-    tileset->setFirstVisibleIndex(1);
+    tileset->setBaseIndex(1);
   }
   // Old tileset used in internal versions (this was added to recover
   // old files, maybe in a future we could remove this code)
diff --git a/src/doc/util.cpp b/src/doc/util.cpp
index 2a3f3e82b..ecddec55d 100644
--- a/src/doc/util.cpp
+++ b/src/doc/util.cpp
@@ -19,14 +19,14 @@ void fix_old_tileset(
   // case we can use this tileset as a new tileset without any
   // conversion.
   if (tileset->size() > 0 && is_empty_image(tileset->get(0).get())) {
-    tileset->setFirstVisibleIndex(1);
+    tileset->setBaseIndex(1);
   }
   else {
     // Add the empty tile in the index = 0
     tileset->insert(0, tileset->makeEmptyTile());
 
     // The tile 1 will be displayed as tile 0 in the editor
-    tileset->setFirstVisibleIndex(0);
+    tileset->setBaseIndex(0);
   }
 }
 
@@ -36,7 +36,7 @@ void fix_old_tilemap(
   const tile_t tileIDMask,
   const tile_t tileFlagsMask)
 {
-  int delta = (tileset->firstVisibleIndex() == 0 ? 1: 0);
+  int delta = (tileset->baseIndex() == 0 ? 1: 0);
 
   // Convert old empty tile (0xffffffff) to new empty tile (index 0 = notile)
   transform_image<TilemapTraits>(