diff --git a/composer.json b/composer.json
index 1537463..f3c9455 100644
--- a/composer.json
+++ b/composer.json
@@ -40,7 +40,7 @@
         "httpsoft/http-message": "^1.1",
         "psr/container": "^2.0",
         "psr/http-factory": "^1.0",
-        "psr/http-message": "^1.0",
+        "psr/http-message": "^1.0|^2.0",
         "psr/http-server-handler": "^1.0",
         "psr/http-server-middleware": "^1.0",
         "psr/simple-cache": "^2.0|^3.0",