diff --git a/src/doctor.ts b/src/doctor.ts
index 65753e6..3b6daee 100644
--- a/src/doctor.ts
+++ b/src/doctor.ts
@@ -30,7 +30,7 @@ export class Doctor {
     );
     const compilerOptions = parsed.options
 
-    const defaultLibFileName = _ts.getDefaultLibFileName(compilerOptions)
+    const defaultLibFileName = ts.getDefaultLibFileName(compilerOptions)
     const libs =  [defaultLibFileName, ...(compilerOptions.lib || [])]
     const allLibs = getAllLibs(uniq(libs))