diff --git a/crates/oxc_isolated_declarations/src/lib.rs b/crates/oxc_isolated_declarations/src/lib.rs
index b6796334e42b1..9799618bbdf14 100644
--- a/crates/oxc_isolated_declarations/src/lib.rs
+++ b/crates/oxc_isolated_declarations/src/lib.rs
@@ -144,6 +144,7 @@ impl<'a> IsolatedDeclarations<'a> {
                         }
                         Declaration::TSModuleDeclaration(decl) => {
                             if decl.kind.is_global() {
+                                self.scope.visit_ts_module_declaration(decl);
                                 transformed_indexes.push(new_stmts.len());
                             }
                         }
diff --git a/crates/oxc_isolated_declarations/tests/fixtures/declare-global.ts b/crates/oxc_isolated_declarations/tests/fixtures/declare-global.ts
index c271fa55e7a99..fd994c73dcb10 100644
--- a/crates/oxc_isolated_declarations/tests/fixtures/declare-global.ts
+++ b/crates/oxc_isolated_declarations/tests/fixtures/declare-global.ts
@@ -1,4 +1,11 @@
+function MyFunction() {
+  return 'here is my function'
+}
+
 declare global {
+  interface Window {
+    MyFunction: typeof MyFunction
+  }
 }
 
 export {}
\ No newline at end of file
diff --git a/crates/oxc_isolated_declarations/tests/snapshots/declare-global.snap b/crates/oxc_isolated_declarations/tests/snapshots/declare-global.snap
index 51bbc0340e3e8..c62c684d53213 100644
--- a/crates/oxc_isolated_declarations/tests/snapshots/declare-global.snap
+++ b/crates/oxc_isolated_declarations/tests/snapshots/declare-global.snap
@@ -4,5 +4,10 @@ input_file: crates/oxc_isolated_declarations/tests/fixtures/declare-global.ts
 ---
 ==================== .D.TS ====================
 
-declare global {}
+declare function MyFunction(): string;
+declare global {
+	interface Window {
+		MyFunction: typeof MyFunction;
+	}
+}
 export {};