diff --git a/core/lib/Drupal/Core/Extension/ThemeInstaller.php b/core/lib/Drupal/Core/Extension/ThemeInstaller.php
index 4993fa1cad..59adbae578 100644
--- a/core/lib/Drupal/Core/Extension/ThemeInstaller.php
+++ b/core/lib/Drupal/Core/Extension/ThemeInstaller.php
@@ -126,12 +126,12 @@ public function install(array $theme_list, $install_dependencies = TRUE) {
       foreach ($theme_list as $theme => $value) {
         $module_dependencies = $theme_data[$theme]->module_dependencies;
         $theme_dependencies = array_diff_key($theme_data[$theme]->requires, $module_dependencies);
-        $missing_module_dependencies = array_diff_key($module_dependencies, $installed_modules);
+        $unmet_module_dependencies = array_diff_key($module_dependencies, $installed_modules);
 
         // Prevent themes with unmet module dependencies from being installed.
-        if (!empty($missing_module_dependencies)) {
-          $missing_module_dependencies_list = implode(', ', array_keys($missing_module_dependencies));
-          throw new MissingDependencyException("Unable to install theme: '$theme' due to missing module dependencies: '$missing_module_dependencies_list.'");
+        if (!empty($unmet_module_dependencies)) {
+          $unmet_module_dependencies_list = implode(', ', array_keys($unmet_module_dependencies));
+          throw new MissingDependencyException("Unable to install theme: '$theme' due to unmet module dependencies: '$unmet_module_dependencies_list.'");
         }
 
         // Add dependencies to the list of themes to install. The new themes
diff --git a/core/modules/system/src/Controller/SystemController.php b/core/modules/system/src/Controller/SystemController.php
index 578a8c743f..dd16ce349a 100644
--- a/core/modules/system/src/Controller/SystemController.php
+++ b/core/modules/system/src/Controller/SystemController.php
@@ -261,19 +261,19 @@ public function themesPage() {
         $modules = $this->moduleExtensionList->getList();
         foreach ($theme->module_dependencies as $dependency => $dependency_object) {
           if ($incompatible = $this->checkDependencyMessage($modules, $dependency, $dependency_object)) {
-            $theme->module_dependencies[$dependency] = $incompatible;
+            $theme->module_dependencies_list[$dependency] = $incompatible;
             $theme->incompatible_module = TRUE;
             continue;
           }
 
           // Only display visible modules.
           if (!empty($modules[$dependency]->hidden)) {
-            unset($theme->module_dependencies[$dependency]);
             continue;
           }
 
           $module_name = $modules[$dependency]->info['name'];
-          $theme->module_dependencies[$dependency] = $modules[$dependency]->status ? $this->t('@module_name', ['@module_name' => $module_name]) : $this->t('@module_name (<span class="admin-disabled">disabled</span>)', ['@module_name' => $module_name]);
+          $theme->module_dependencies_list[$dependency] = $modules[$dependency]->status ? $this->t('@module_name', ['@module_name' => $module_name]) : $this->t('@module_name (<span class="admin-disabled">disabled</span>)', ['@module_name' => $module_name]);
+
           // Create an additional property that contains only disabled module
           // dependencies. This will determine if it is possible to install the
           // theme, or if modules must first be enabled.
diff --git a/core/modules/system/system.admin.inc b/core/modules/system/system.admin.inc
index ea33414fe9..206ed3cdf3 100644
--- a/core/modules/system/system.admin.inc
+++ b/core/modules/system/system.admin.inc
@@ -304,9 +304,9 @@ function template_preprocess_system_themes_page(&$variables) {
       $current_theme['is_default'] = $theme->is_default;
       $current_theme['is_admin'] = $theme->is_admin;
 
-      $current_theme['module_dependencies'] = !empty($theme->module_dependencies) ? [
+      $current_theme['module_dependencies'] = !empty($theme->module_dependencies_list) ? [
         '#theme' => 'item_list',
-        '#items' => $theme->module_dependencies,
+        '#items' => $theme->module_dependencies_list,
         '#context' => ['list_style' => 'comma-list'],
       ] : [];
 
diff --git a/core/modules/system/tests/src/Functional/Form/ModulesListFormWebTest.php b/core/modules/system/tests/src/Functional/Form/ModulesListFormWebTest.php
index a210cd37a9..cef12ffcc7 100644
--- a/core/modules/system/tests/src/Functional/Form/ModulesListFormWebTest.php
+++ b/core/modules/system/tests/src/Functional/Form/ModulesListFormWebTest.php
@@ -33,13 +33,7 @@ protected function setUp() {
    * Tests the module list form.
    */
   public function testModuleListForm() {
-    $this->drupalLogin(
-      $this->drupalCreateUser(
-        ['administer modules', 'administer permissions']
-      )
-    );
-    $this->drupalGet('admin/modules');
-    $this->assertResponse('200');
+    $this->createUserAdministerModules();
 
     // Check that system_test's configure link was rendered correctly.
     $this->assertFieldByXPath("//a[contains(@href, '/system-test/configure/bar') and text()='Configure ']/span[contains(@class, 'visually-hidden') and text()='the System test module']");
@@ -65,13 +59,7 @@ public function testModulesListFormWithInvalidInfoFile() {
     mkdir($path, 0777, TRUE);
     file_put_contents("$path/broken.info.yml", $broken_info_yml);
 
-    $this->drupalLogin(
-      $this->drupalCreateUser(
-        ['administer modules', 'administer permissions']
-      )
-    );
-    $this->drupalGet('admin/modules');
-    $this->assertSession()->statusCodeEquals(200);
+    $this->createUserAdministerModules();
 
     // Confirm that the error message is shown.
     $this->assertSession()
@@ -81,4 +69,33 @@ public function testModulesListFormWithInvalidInfoFile() {
     $this->assertSession()->elementExists('xpath', '//input[@name="text"]');
   }
 
+  /**
+   * Confirm that module 'Required By' descriptions include dependent themes.
+   */
+  public function testRequiredByThemeMessage() {
+    $this->createUserAdministerModules();
+    $module_theme_depends_on_description = $this->getSession()->getPage()->findAll('css', '#edit-modules-test-module-required-by-theme-enable-description .admin-requirements li:contains("Test Theme Depending on Modules (Theme) (Disabled)")');
+
+    // Confirm that that 'Test Theme Depending on Modules' is listed as being
+    // required by the module 'Test Module Required by Theme'.
+    $this->assertCount(1, $module_theme_depends_on_description);
+
+    // Confirm that the required by message does not appear anywhere else.
+    $this->assertSession()->pageTextContains('Test Theme Depending on Modules (Theme) (Disabled)');
+  }
+
+  /**
+   * Creates user that can administer modules then visits `admin/modules`.
+   */
+  protected function createUserAdministerModules() {
+    $this->drupalLogin(
+      $this->drupalCreateUser(
+        ['administer modules', 'administer permissions']
+      )
+    );
+
+    $this->drupalGet('admin/modules');
+    $this->assertSession()->statusCodeEquals(200);
+  }
+
 }