diff --git a/composer.json b/composer.json
index e4cb6977..c97c2db9 100644
--- a/composer.json
+++ b/composer.json
@@ -3,13 +3,13 @@
     "description": "PHP core functions that throw exceptions instead of returning FALSE on error",
     "license": "MIT",
     "autoload": {
-        "psr-4": {
-            "Safe\\": [
-                "lib/",
-                "deprecated/",
-                "generated/"
-            ]
-        },
+        "classmap": [
+            "lib/DateTime.php",
+            "lib/DateTimeImmutable.php",
+            "lib/Exceptions/",
+            "deprecated/Exceptions/",
+            "generated/Exceptions/"
+        ],
         "files": [
             "deprecated/apc.php",
             "deprecated/array.php",