diff --git a/core/lib/Drupal/Core/Theme/Registry.php b/core/lib/Drupal/Core/Theme/Registry.php
index b1c463c..8d6141b 100644
--- a/core/lib/Drupal/Core/Theme/Registry.php
+++ b/core/lib/Drupal/Core/Theme/Registry.php
@@ -600,8 +600,8 @@ protected function postProcessExtension(array &$cache, ActiveTheme $theme) {
     }
     $prefixes[] = $theme->getName();
 
-    // Collect all variable processor functions in the correct order.
-    $processors = [];
+    // Collect all variable preprocess functions in the correct order.
+    $suggestion_level = [];
     $matches = [];
     // Look for functions named according to the pattern and add them if they
     // have matching hooks in the registry.
@@ -612,49 +612,50 @@ protected function postProcessExtension(array &$cache, ActiveTheme $theme) {
         continue;
       }
       // Add the function and the name of the associated theme hook to the list
-      // of processors if a matching base hook is found.
+      // of preprocess functions grouped by suggestion specificity if a matching
+      // base hook is found.
       foreach ($grouped_functions[$first_prefix] as $candidate) {
         if (preg_match("/^{$prefix}_preprocess_(((?:[^_]++|_(?!_))+)__.*)/", $candidate, $matches)) {
-          $processors[$candidate] = $matches[1];
+          $level = substr_count($matches[1], '__');
+          $suggestion_level[$level][$candidate] = $matches[1];
         }
       }
     }
 
-    // Add missing variable processors. This is needed for hooks that do not
+    // Add missing variable preprocessors. This is needed for hooks that do not
     // explicitly register the hook. For example, when a theme contains a
-    // variable process function but it does not implement a template, it will
-    // go missing. This will add the expected function. It also allows modules
-    // or themes to have a variable process function based on a pattern even if
-    // the hook does not exist.
-    foreach ($processors as $processor => $hook) {
-      if (isset($cache[$hook]['preprocess functions']) && !in_array($hook, $cache[$hook]['preprocess functions'])) {
-        // Add missing processor to existing hook.
-        $cache[$hook]['preprocess functions'][] = $processor;
-      }
-      elseif (!isset($cache[$hook]) && strpos($hook, '__')) {
-        // Process non-existing hook and register it.
-        // Search for the base hook.
-        $base_hook = $hook;
-        while (!isset($cache[$base_hook]) && $pos = strrpos($base_hook, '__')) {
-          $base_hook = substr($base_hook, 0, $pos);
-          // If the current hook is based on a pattern, get the base hook.
-          if (isset($cache[$hook]['base hook'])) {
-            $base_hook = $cache[$hook]['base hook'];
-          }
-          // If base hook exists clone of it for the preprocess function
-          // without a template.
-          // @see https://www.drupal.org/node/2457295
-          if (isset($cache[$base_hook])) {
-            $cache[$hook] = $cache[$base_hook];
-            $cache[$hook]['base hook'] = $base_hook;
-            $cache[$hook]['preprocess functions'][] = $processor;
+    // variable preprocess function but it does not implement a template, it
+    // will go missing. This will add the expected function. It also allows
+    // modules or themes to have a variable process function based on a pattern
+    // even if the hook does not exist.
+    for ($level = 1; $level <= count($suggestion_level); $level++) {
+      foreach ($suggestion_level[$level] as $preprocessor => $hook) {
+        if (isset($cache[$hook]['preprocess functions']) && !in_array($hook, $cache[$hook]['preprocess functions'])) {
+          // Add missing preprocessor to existing hook.
+          $cache[$hook]['preprocess functions'][] = $preprocessor;
+        }
+        elseif (!isset($cache[$hook]) && strpos($hook, '__')) {
+          // Process non-existing hook and register it.
+          // Look for a previously defined hook that is either a less specific
+          // suggestion hook or the base hook.
+          $previous_hook = $hook;
+          while (!isset($cache[$previous_hook]) && $pos = strrpos($previous_hook, '__')) {
+            $previous_hook = substr($previous_hook, 0, $pos);
+            // If base hook exists clone of it for the preprocess function
+            // without a template.
+            // @see https://www.drupal.org/node/2457295
+            if (isset($cache[$previous_hook])) {
+              $cache[$hook] = $cache[$previous_hook];
+              $cache[$hook]['base hook'] = $previous_hook;
+              $cache[$hook]['preprocess functions'][] = $preprocessor;
+            }
           }
         }
       }
     }
-    // Inherit all base hook variable processors into pattern hooks.
+    // Inherit all base hook variable preprocess functions into pattern hooks.
     // This ensures that derivative hooks have a complete set of variable
-    // process functions.
+    // preprocess functions.
     foreach ($cache as $hook => $info) {
       // The 'base hook' is only applied to derivative hooks already registered
       // from a pattern. This is typically set from
diff --git a/core/modules/system/tests/modules/theme_test/theme_test.module b/core/modules/system/tests/modules/theme_test/theme_test.module
index cacdd73..8b820c3 100644
--- a/core/modules/system/tests/modules/theme_test/theme_test.module
+++ b/core/modules/system/tests/modules/theme_test/theme_test.module
@@ -116,7 +116,6 @@ function theme_test_preprocess_theme_test_preprocess_suggestions__monkey(&$varia
   $variables['foo'] = 'Monkey';
 }
 
-
 /**
  * Prepares variables for test render element templates.
  *