diff --git a/src/server/protocol.ts b/src/server/protocol.ts
index cabe7dcd55d..ac4d5a9bf0c 100644
--- a/src/server/protocol.ts
+++ b/src/server/protocol.ts
@@ -2086,6 +2086,11 @@ namespace ts.server.protocol {
          * Then either that enum/class or a namespace containing it will be the recommended symbol.
          */
         isRecommended?: true;
+        /**
+         * If true, this completion was generated from traversing the name table of an unchecked JS file,
+         * and therefore may not be accurate.
+         */
+        isUncheckedCompletion?: true;
     }
 
     /**
diff --git a/src/services/completions.ts b/src/services/completions.ts
index 471d8e4c142..b97dabfb32f 100644
--- a/src/services/completions.ts
+++ b/src/services/completions.ts
@@ -310,7 +310,8 @@ namespace ts.Completions {
                     name: realName,
                     kind: ScriptElementKind.warning,
                     kindModifiers: "",
-                    sortText: SortText.JavascriptIdentifiers
+                    sortText: SortText.JavascriptIdentifiers,
+                    isUncheckedCompletion: true
                 });
             }
         });
diff --git a/src/services/types.ts b/src/services/types.ts
index 3a1627c247f..82a90afa12c 100644
--- a/src/services/types.ts
+++ b/src/services/types.ts
@@ -988,6 +988,7 @@ namespace ts {
         hasAction?: true;
         source?: string;
         isRecommended?: true;
+        isUncheckedCompletion?: true;
     }
 
     export interface CompletionEntryDetails {