diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 861279b2225..82c3eaaf04b 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -737,7 +737,8 @@ namespace ts {
             const useFile = getSourceFileOfNode(usage);
             if (declarationFile !== useFile) {
                 if ((modulekind && (declarationFile.externalModuleIndicator || useFile.externalModuleIndicator)) ||
-                    (!compilerOptions.outFile && !compilerOptions.out)) {
+                    (!compilerOptions.outFile && !compilerOptions.out) ||
+                    isInAmbientContext(declaration)) {
                     // nodes are in different files and order cannot be determined
                     return true;
                 }