diff --git a/src/global.d.ts b/src/global.d.ts
new file mode 100644
index 00000000..5b172476
--- /dev/null
+++ b/src/global.d.ts
@@ -0,0 +1,15 @@
+/**
+ * Global type declarations for Brainy
+ */
+
+// Extend the globalThis interface to include the __ENV__ property
+declare global {
+  var __ENV__: {
+    isBrowser: boolean;
+    isNode: string | false;
+    isServerless: boolean;
+  };
+}
+
+// This export is needed to make this file a module
+export {};