diff --git a/data/strings/en.ini b/data/strings/en.ini
index 1ea1b13bc7d..cc15c6b729f 100644
--- a/data/strings/en.ini
+++ b/data/strings/en.ini
@@ -90,6 +90,7 @@ job_working = {0}<<Working...||&Cancel
 nothing_to_report = Crash Report<<Nothing to report||&OK
 install_extension = Warning\n<<Do you really want to install the given extension?\n<<"{0}"\n||&Install||&Cancel
 uninstall_extension_warning = Warning\n<<Do you really want to uninstall "{0}" extension?\n||&Yes||&No
+cannot_install_default_extension = Error\n<<This theme cannot be installed because its name matches the default aseprite theme\n||&OK
 unknown_output_file_format_error = Aseprite\n<<Unknown file format "{0}" in output filename\n||&OK
 update_screen_ui_scaling_with_theme_values = Update Screen/UI Scaling\n<<The new theme "{0}" wants to adjust some values for you:\n<<  Screen Scaling: {1}% -> {2}%\n<<  UI Scaling: {3}% -> {4}%\n<<Allow these changes?\n||&Adjust Scaling||&Don't Adjust Scaling
 update_extension = Update Extension\n<<The extension "{0}" already exists.\n<<Do you want to {1} from v{2} to v{3}?\n||&Yes||&No
diff --git a/src/app/commands/cmd_options.cpp b/src/app/commands/cmd_options.cpp
index 2a474be8f23..71291144edb 100644
--- a/src/app/commands/cmd_options.cpp
+++ b/src/app/commands/cmd_options.cpp
@@ -940,6 +940,18 @@ class OptionsWindow : public app::gen::Options {
       }
     }
 
+    // Get the extension information from the compressed
+    // package.json file.
+    ExtensionInfo info =
+      App::instance()->extensions().getCompressedExtensionInfo(filename);
+    // Check if the filename corresponds to aseprite-default theme
+    if (base::string_to_lower(info.name) ==
+        kAsepriteDefaultThemeExtensionName) {
+      ui::Alert::show(
+        fmt::format(Strings::alerts_cannot_install_default_extension()));
+      return false;
+    }
+
     // Install?
     if (ui::Alert::show(
           fmt::format(Strings::alerts_install_extension(), filename)) != 1)
@@ -1760,7 +1772,7 @@ class OptionsWindow : public app::gen::Options {
     return paths;
   }
 
-  static base::paths createUserDirPaths(const base::paths dirNames) {
+  static base::paths getUserDirPaths(const base::paths dirNames) {
     ResourceFinder rf;
     for (auto& fn : dirNames)
       rf.includeUserDir(fn.c_str());
@@ -1791,7 +1803,7 @@ class OptionsWindow : public app::gen::Options {
     if (!e->isDefaultTheme())
       return false;
     auto userThemePaths =
-      createUserDirPaths({"extensions", skin::SkinTheme::kThemesFolderName});
+      getUserDirPaths({"extensions", skin::SkinTheme::kThemesFolderName});
     for (auto& p : userThemePaths) {
       // Has the user path (p) the same path of the extension (e->path())?
       if (std::strncmp(e->path().c_str(), p.c_str(), p.size()) == 0)
diff --git a/src/app/extensions.cpp b/src/app/extensions.cpp
index 768a9435e89..fa5684de618 100644
--- a/src/app/extensions.cpp
+++ b/src/app/extensions.cpp
@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2020-2023  Igara Studio S.A.
+// Copyright (C) 2020-2024  Igara Studio S.A.
 // Copyright (C) 2017-2018  David Capello
 //
 // This program is distributed under the terms of
@@ -56,7 +56,6 @@ namespace {
 const char* kPackageJson = "package.json";
 const char* kInfoJson = "__info.json";
 const char* kPrefLua = "__pref.lua";
-const char* kAsepriteDefaultThemeExtensionName = "aseprite-theme";
 
 class ReadArchive {
 public:
diff --git a/src/app/extensions.h b/src/app/extensions.h
index 8123cdbfc47..3d7ca245726 100644
--- a/src/app/extensions.h
+++ b/src/app/extensions.h
@@ -21,6 +21,10 @@ namespace ui {
   class Widget;
 }
 
+namespace {
+  const char* kAsepriteDefaultThemeExtensionName = "aseprite-theme";
+}
+
 namespace app {
 
   // Key=id