diff --git a/src/compiler/moduleNameResolver.ts b/src/compiler/moduleNameResolver.ts
index 4ea590977e1..63cfc84b3d6 100644
--- a/src/compiler/moduleNameResolver.ts
+++ b/src/compiler/moduleNameResolver.ts
@@ -995,7 +995,7 @@ namespace ts {
     export function getPackageNameFromAtTypesDirectory(mangledName: string): string {
         const withoutAtTypePrefix = removePrefix(mangledName, "@types/");
         if (withoutAtTypePrefix !== mangledName) {
-            return withoutAtTypePrefix.indexOf("__") !== -1 ?
+            return withoutAtTypePrefix.indexOf(mangledScopedPackageSeparator) !== -1 ?
                 "@" + withoutAtTypePrefix.replace(mangledScopedPackageSeparator, ts.directorySeparator) :
                 withoutAtTypePrefix;
         }