diff --git a/packages/language-service/tsconfig.json b/packages/language-service/tsconfig.json
index 930b6898f7c..0057d9e1f3e 100644
--- a/packages/language-service/tsconfig.json
+++ b/packages/language-service/tsconfig.json
@@ -4,6 +4,7 @@
     "types": ["node"],
     "paths": {
       "@angular/*": ["../*"],
+      // compiler-cli specific mapping is present to allow deep importing into the compiler code.
       "@angular/compiler-cli": ["../compiler-cli"],
       "@angular/compiler-cli/*": ["../compiler-cli/*"]
     }