diff --git a/config/pkg/ext/builtin-extensions.yml b/config/pkg/ext/builtin-extensions.yml
index bdb97507..9b39ae8f 100644
--- a/config/pkg/ext/builtin-extensions.yml
+++ b/config/pkg/ext/builtin-extensions.yml
@@ -229,6 +229,10 @@ ext-readline:
     build-static: true
 ext-session:
   type: php-extension
+ext-shmop:
+  type: php-extension
+  php-extension:
+    build-with-php: true
 ext-sockets:
   type: php-extension
 ext-sqlite3:
diff --git a/src/StaticPHP/Config/PackageConfig.php b/src/StaticPHP/Config/PackageConfig.php
index c4f22a52..0e2d0af1 100644
--- a/src/StaticPHP/Config/PackageConfig.php
+++ b/src/StaticPHP/Config/PackageConfig.php
@@ -23,6 +23,7 @@ class PackageConfig
         if (!is_dir($dir)) {
             throw new WrongUsageException("Directory {$dir} does not exist, cannot load pkg.json config.");
         }
+        $dir = rtrim($dir, '/');
         $loaded = [];
         $files = FileSystem::scanDirFiles($dir, false);
         if (is_array($files)) {
diff --git a/src/StaticPHP/Util/FileSystem.php b/src/StaticPHP/Util/FileSystem.php
index c8da5353..3015b489 100644
--- a/src/StaticPHP/Util/FileSystem.php
+++ b/src/StaticPHP/Util/FileSystem.php
@@ -481,7 +481,7 @@ class FileSystem
     public static function fullpath(string $path, string $relative_path_base): string
     {
         if (FileSystem::isRelativePath($path)) {
-            $path = $relative_path_base . DIRECTORY_SEPARATOR . $path;
+            $path = rtrim($relative_path_base, '/') . DIRECTORY_SEPARATOR . $path;
         }
         if (!file_exists($path)) {
             throw new FileSystemException("Path does not exist: {$path}");