diff --git a/modules/ui_patterns_library/src/Plugin/UiPatterns/Pattern/LibraryPattern.php b/modules/ui_patterns_library/src/Plugin/UiPatterns/Pattern/LibraryPattern.php
index f57aad21..f2c8102d 100644
--- a/modules/ui_patterns_library/src/Plugin/UiPatterns/Pattern/LibraryPattern.php
+++ b/modules/ui_patterns_library/src/Plugin/UiPatterns/Pattern/LibraryPattern.php
@@ -78,7 +78,7 @@ protected function processCustomThemeHookProperty(PatternDefinition $definition)
       $module = $this->moduleHandler->getModule($definition->getProvider());
       $return['path'] = $module->getPath() . '/templates';
       if ($this->templateExists($definition->getBasePath(), $definition->getTemplate())) {
-        $return['path'] = str_replace($this->root, '', $definition->getBasePath());
+        $return['path'] = str_replace($this->root . DIRECTORY_SEPARATOR, '', $definition->getBasePath());
       }
     }
     return $return;
diff --git a/src/Plugin/PatternBase.php b/src/Plugin/PatternBase.php
index bd773d96..f8354357 100644
--- a/src/Plugin/PatternBase.php
+++ b/src/Plugin/PatternBase.php
@@ -79,7 +79,7 @@ public function getLibraryDefinitions() {
 
     // Attach pattern base path to assets.
     if (!empty($definition['base path'])) {
-      $base_path = str_replace($this->root, '', $definition['base path']);
+      $base_path = str_replace($this->root . DIRECTORY_SEPARATOR, '', $definition['base path']);
       $this->processLibraries($items, $base_path);
     }