diff --git a/composer.json b/composer.json
index bbcf36de8..9947ec8a3 100644
--- a/composer.json
+++ b/composer.json
@@ -10,7 +10,7 @@
     "require-dev": {
         "squizlabs/php_codesniffer": "^2.2 || ^3.0.2",
         "phpcompatibility/php-compatibility": "*",
-        "yoast/phpunit-polyfills": "^1.0"
+        "yoast/phpunit-polyfills": "^1.0.1"
     },
     "prefer-stable" : true,
     "minimum-stability": "dev",
diff --git a/composer.lock b/composer.lock
index 44abef627..b62e284fa 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "b7415e1ffd271acf46f566f53fcc07e8",
+    "content-hash": "33ed3955dccb57a048e54eec04c20205",
     "packages": [
         {
             "name": "kornrunner/blurhash",