diff --git a/src/service/transformer/declaration-tree-shaker/reference/is-referenced/is-referenced.ts b/src/service/transformer/declaration-tree-shaker/reference/is-referenced/is-referenced.ts
index 686bcf3a..a24419b4 100644
--- a/src/service/transformer/declaration-tree-shaker/reference/is-referenced/is-referenced.ts
+++ b/src/service/transformer/declaration-tree-shaker/reference/is-referenced/is-referenced.ts
@@ -1,4 +1,4 @@
-import {forEachChild, isExportAssignment, isExportDeclaration, isExportSpecifier, isIdentifier, Node} from "typescript";
+import {forEachChild, isExportAssignment, isExportDeclaration, isExportSpecifier, isIdentifier, isModuleDeclaration, Node} from "typescript";
 import {IsReferencedOptions} from "./is-referenced-options";
 import {nodeContainsChild} from "../../util/node-contains-child";
 import {getIdentifiersForNode} from "../../util/get-identifiers-for-node";
@@ -41,7 +41,7 @@ function visitNode(currentNode: Node, options: ReferenceVisitorOptions): void {
  */
 export function isReferenced<T extends Node>({seenNodes = new Set(), ...options}: IsReferencedOptions<T>): boolean {
 	// Exports are always referenced and should never be removed
-	if (isExportDeclaration(options.node) || isExportSpecifier(options.node) || isExportAssignment(options.node) || hasExportModifier(options.node)) return true;
+	if (isExportDeclaration(options.node) || isExportSpecifier(options.node) || isExportAssignment(options.node) || hasExportModifier(options.node) || isModuleDeclaration(options.node)) return true;
 
 	// If it has been computed previously, use the cached result
 	if (options.cache.hasReferencesCache.has(options.node)) {
diff --git a/src/service/transformer/declaration-tree-shaker/util/is-ambient-module-root-level-node.ts b/src/service/transformer/declaration-tree-shaker/util/is-ambient-module-root-level-node.ts
index caeccdab..f3574c66 100644
--- a/src/service/transformer/declaration-tree-shaker/util/is-ambient-module-root-level-node.ts
+++ b/src/service/transformer/declaration-tree-shaker/util/is-ambient-module-root-level-node.ts
@@ -1,13 +1,14 @@
 import {
-	Node,
 	isClassDeclaration,
 	isEnumDeclaration,
 	isExportAssignment,
 	isExportDeclaration,
 	isFunctionDeclaration,
 	isInterfaceDeclaration,
+	isModuleDeclaration,
 	isTypeAliasDeclaration,
-	isVariableStatement
+	isVariableStatement,
+	Node
 } from "typescript";
 
 /**
@@ -20,6 +21,7 @@ export function isAmbientModuleRootLevelNode(node: Node): boolean {
 		isExportDeclaration(node) ||
 		isExportAssignment(node) ||
 		isInterfaceDeclaration(node) ||
+		isModuleDeclaration(node) ||
 		isEnumDeclaration(node) ||
 		isClassDeclaration(node) ||
 		isTypeAliasDeclaration(node) ||