diff --git a/composer.json b/composer.json
index f1ef70e5..1c3eb17b 100644
--- a/composer.json
+++ b/composer.json
@@ -23,11 +23,11 @@
         "fguillot/picofeed": ">=0.1.31",
         "jkingweb/druuid": "^3.0.0",
         "phpseclib/phpseclib": "^2.0.4",
-        "hosteurope/password-generator": "^1.0.1",
-        "webmozart/glob": "^4.1.0"
+        "hosteurope/password-generator": "^1.0.1"
     },
     "require-dev": {
         "mikey179/vfsStream": "^1.6.4",
+        "webmozart/glob": "^4.1.0",
         "phake/phake": "^2.3.2",
         "phpunit/phpunit": "^6.0.5"
     },
diff --git a/composer.lock b/composer.lock
index 945279b9..b4aa0a60 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#composer-lock-the-lock-file",
         "This file is @generated automatically"
     ],
-    "content-hash": "cd32c438fa1e530cc51e9ba5b608123c",
+    "content-hash": "716302e991c06ae6308829749b16a078",
     "packages": [
         {
             "name": "fguillot/picofeed",
@@ -236,149 +236,6 @@
             ],
             "time": "2017-05-08T05:58:35+00:00"
         },
-        {
-            "name": "webmozart/assert",
-            "version": "1.2.0",
-            "source": {
-                "type": "git",
-                "url": "https://github.com/webmozart/assert.git",
-                "reference": "2db61e59ff05fe5126d152bd0655c9ea113e550f"
-            },
-            "dist": {
-                "type": "zip",
-                "url": "https://api.github.com/repos/webmozart/assert/zipball/2db61e59ff05fe5126d152bd0655c9ea113e550f",
-                "reference": "2db61e59ff05fe5126d152bd0655c9ea113e550f",
-                "shasum": ""
-            },
-            "require": {
-                "php": "^5.3.3 || ^7.0"
-            },
-            "require-dev": {
-                "phpunit/phpunit": "^4.6",
-                "sebastian/version": "^1.0.1"
-            },
-            "type": "library",
-            "extra": {
-                "branch-alias": {
-                    "dev-master": "1.3-dev"
-                }
-            },
-            "autoload": {
-                "psr-4": {
-                    "Webmozart\\Assert\\": "src/"
-                }
-            },
-            "notification-url": "https://packagist.org/downloads/",
-            "license": [
-                "MIT"
-            ],
-            "authors": [
-                {
-                    "name": "Bernhard Schussek",
-                    "email": "bschussek@gmail.com"
-                }
-            ],
-            "description": "Assertions to validate method input/output with nice error messages.",
-            "keywords": [
-                "assert",
-                "check",
-                "validate"
-            ],
-            "time": "2016-11-23T20:04:58+00:00"
-        },
-        {
-            "name": "webmozart/glob",
-            "version": "4.1.0",
-            "source": {
-                "type": "git",
-                "url": "https://github.com/webmozart/glob.git",
-                "reference": "3cbf63d4973cf9d780b93d2da8eec7e4a9e63bbe"
-            },
-            "dist": {
-                "type": "zip",
-                "url": "https://api.github.com/repos/webmozart/glob/zipball/3cbf63d4973cf9d780b93d2da8eec7e4a9e63bbe",
-                "reference": "3cbf63d4973cf9d780b93d2da8eec7e4a9e63bbe",
-                "shasum": ""
-            },
-            "require": {
-                "php": "^5.3.3|^7.0",
-                "webmozart/path-util": "^2.2"
-            },
-            "require-dev": {
-                "phpunit/phpunit": "^4.6",
-                "sebastian/version": "^1.0.1",
-                "symfony/filesystem": "^2.5"
-            },
-            "type": "library",
-            "extra": {
-                "branch-alias": {
-                    "dev-master": "4.1-dev"
-                }
-            },
-            "autoload": {
-                "psr-4": {
-                    "Webmozart\\Glob\\": "src/"
-                }
-            },
-            "notification-url": "https://packagist.org/downloads/",
-            "license": [
-                "MIT"
-            ],
-            "authors": [
-                {
-                    "name": "Bernhard Schussek",
-                    "email": "bschussek@gmail.com"
-                }
-            ],
-            "description": "A PHP implementation of Ant's glob.",
-            "time": "2015-12-29T11:14:33+00:00"
-        },
-        {
-            "name": "webmozart/path-util",
-            "version": "2.3.0",
-            "source": {
-                "type": "git",
-                "url": "https://github.com/webmozart/path-util.git",
-                "reference": "d939f7edc24c9a1bb9c0dee5cb05d8e859490725"
-            },
-            "dist": {
-                "type": "zip",
-                "url": "https://api.github.com/repos/webmozart/path-util/zipball/d939f7edc24c9a1bb9c0dee5cb05d8e859490725",
-                "reference": "d939f7edc24c9a1bb9c0dee5cb05d8e859490725",
-                "shasum": ""
-            },
-            "require": {
-                "php": ">=5.3.3",
-                "webmozart/assert": "~1.0"
-            },
-            "require-dev": {
-                "phpunit/phpunit": "^4.6",
-                "sebastian/version": "^1.0.1"
-            },
-            "type": "library",
-            "extra": {
-                "branch-alias": {
-                    "dev-master": "2.3-dev"
-                }
-            },
-            "autoload": {
-                "psr-4": {
-                    "Webmozart\\PathUtil\\": "src/"
-                }
-            },
-            "notification-url": "https://packagist.org/downloads/",
-            "license": [
-                "MIT"
-            ],
-            "authors": [
-                {
-                    "name": "Bernhard Schussek",
-                    "email": "bschussek@gmail.com"
-                }
-            ],
-            "description": "A robust cross-platform utility for normalizing, comparing and modifying file paths.",
-            "time": "2015-12-17T08:42:14+00:00"
-        },
         {
             "name": "zendframework/zendxml",
             "version": "1.0.2",
@@ -1337,16 +1194,16 @@
         },
         {
             "name": "sebastian/diff",
-            "version": "1.4.2",
+            "version": "1.4.3",
             "source": {
                 "type": "git",
                 "url": "https://github.com/sebastianbergmann/diff.git",
-                "reference": "3c7d21999e815cdfac70c6c7d79d3a9cb1bc7bc2"
+                "reference": "7f066a26a962dbe58ddea9f72a4e82874a3975a4"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/sebastianbergmann/diff/zipball/3c7d21999e815cdfac70c6c7d79d3a9cb1bc7bc2",
-                "reference": "3c7d21999e815cdfac70c6c7d79d3a9cb1bc7bc2",
+                "url": "https://api.github.com/repos/sebastianbergmann/diff/zipball/7f066a26a962dbe58ddea9f72a4e82874a3975a4",
+                "reference": "7f066a26a962dbe58ddea9f72a4e82874a3975a4",
                 "shasum": ""
             },
             "require": {
@@ -1385,7 +1242,7 @@
             "keywords": [
                 "diff"
             ],
-            "time": "2017-05-18T13:44:30+00:00"
+            "time": "2017-05-22T07:24:03+00:00"
         },
         {
             "name": "sebastian/environment",
@@ -1778,6 +1635,149 @@
             ],
             "description": "A small library for converting tokenized PHP source code into XML and potentially other formats",
             "time": "2017-04-07T12:08:54+00:00"
+        },
+        {
+            "name": "webmozart/assert",
+            "version": "1.2.0",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/webmozart/assert.git",
+                "reference": "2db61e59ff05fe5126d152bd0655c9ea113e550f"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/webmozart/assert/zipball/2db61e59ff05fe5126d152bd0655c9ea113e550f",
+                "reference": "2db61e59ff05fe5126d152bd0655c9ea113e550f",
+                "shasum": ""
+            },
+            "require": {
+                "php": "^5.3.3 || ^7.0"
+            },
+            "require-dev": {
+                "phpunit/phpunit": "^4.6",
+                "sebastian/version": "^1.0.1"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "1.3-dev"
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "Webmozart\\Assert\\": "src/"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Bernhard Schussek",
+                    "email": "bschussek@gmail.com"
+                }
+            ],
+            "description": "Assertions to validate method input/output with nice error messages.",
+            "keywords": [
+                "assert",
+                "check",
+                "validate"
+            ],
+            "time": "2016-11-23T20:04:58+00:00"
+        },
+        {
+            "name": "webmozart/glob",
+            "version": "4.1.0",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/webmozart/glob.git",
+                "reference": "3cbf63d4973cf9d780b93d2da8eec7e4a9e63bbe"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/webmozart/glob/zipball/3cbf63d4973cf9d780b93d2da8eec7e4a9e63bbe",
+                "reference": "3cbf63d4973cf9d780b93d2da8eec7e4a9e63bbe",
+                "shasum": ""
+            },
+            "require": {
+                "php": "^5.3.3|^7.0",
+                "webmozart/path-util": "^2.2"
+            },
+            "require-dev": {
+                "phpunit/phpunit": "^4.6",
+                "sebastian/version": "^1.0.1",
+                "symfony/filesystem": "^2.5"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "4.1-dev"
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "Webmozart\\Glob\\": "src/"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Bernhard Schussek",
+                    "email": "bschussek@gmail.com"
+                }
+            ],
+            "description": "A PHP implementation of Ant's glob.",
+            "time": "2015-12-29T11:14:33+00:00"
+        },
+        {
+            "name": "webmozart/path-util",
+            "version": "2.3.0",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/webmozart/path-util.git",
+                "reference": "d939f7edc24c9a1bb9c0dee5cb05d8e859490725"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/webmozart/path-util/zipball/d939f7edc24c9a1bb9c0dee5cb05d8e859490725",
+                "reference": "d939f7edc24c9a1bb9c0dee5cb05d8e859490725",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.3.3",
+                "webmozart/assert": "~1.0"
+            },
+            "require-dev": {
+                "phpunit/phpunit": "^4.6",
+                "sebastian/version": "^1.0.1"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "2.3-dev"
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "Webmozart\\PathUtil\\": "src/"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Bernhard Schussek",
+                    "email": "bschussek@gmail.com"
+                }
+            ],
+            "description": "A robust cross-platform utility for normalizing, comparing and modifying file paths.",
+            "time": "2015-12-17T08:42:14+00:00"
         }
     ],
     "aliases": [],
diff --git a/lib/Lang.php b/lib/Lang.php
index 1ca84e16..5b57813f 100644
--- a/lib/Lang.php
+++ b/lib/Lang.php
@@ -1,7 +1,6 @@
 <?php
 declare(strict_types=1);
 namespace JKingWeb\Arsse;
-use Webmozart\Glob\Glob;
 
 class Lang {
     const DEFAULT = "en"; // fallback locale
@@ -110,13 +109,16 @@ class Lang {
         return true;
     }
 
+    protected function globFiles(string $path): array {
+        // we wrap PHP's glob function in this method so that unit tests may override it
+        return glob($path."*.php");
+    }
+
     protected function listFiles(): array {
-        $out = glob($this->path."*.php");
-        // built-in glob doesn't work with vfsStream (and this other glob doesn't seem to work with Windows paths), so we try both
-        if(empty($out)) $out = Glob::glob($this->path."*.php"); // FIXME: we should just mock glob() in tests instead and make this a dev dependency
+        $out = $this->globFiles($this->path."*.php");
         // trim the returned file paths to return just the language tag
         $out = array_map(function($file) {
-            $file = str_replace(DIRECTORY_SEPARATOR, "/", $file);
+            $file = str_replace(DIRECTORY_SEPARATOR, "/", $file); // we replace the directory separator because we don't use native paths in testing
             $file = substr($file, strrpos($file, "/")+1);
             return strtolower(substr($file,0,strrpos($file,".")));
         },$out);
diff --git a/tests/lib/Lang/Setup.php b/tests/lib/Lang/Setup.php
index b98d450f..45ee5509 100644
--- a/tests/lib/Lang/Setup.php
+++ b/tests/lib/Lang/Setup.php
@@ -34,7 +34,7 @@ trait Setup {
         // set up a file without read access
         chmod($this->path."ru.php", 0000);
         // make the test Lang class use the vfs files
-        $this->l = new Lang($this->path);
+        $this->l = new TestLang($this->path);
         // create a mock Lang object so as not to create a dependency loop
         $this->clearData(false);
         Data::$l = Phake::mock(Lang::class);
diff --git a/tests/lib/Lang/TestLang.php b/tests/lib/Lang/TestLang.php
new file mode 100644
index 00000000..0d482ca8
--- /dev/null
+++ b/tests/lib/Lang/TestLang.php
@@ -0,0 +1,11 @@
+<?php
+declare(strict_types=1);
+namespace JKingWeb\Arsse\Test\Lang;
+use Webmozart\Glob\Glob;
+
+class TestLang extends \JKingWeb\Arsse\Lang {
+
+    protected function globFiles(string $path): array {
+        return Glob::glob($this->path."*.php");
+    }
+}
\ No newline at end of file