diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index b3b6557c98b..db95eb9bc17 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -9640,7 +9640,7 @@ namespace ts {
                     }
                 }
 
-                let thisType = getThisTypeOfDeclaration(container) || getContextualThisParameterType(container);
+                const thisType = getThisTypeOfDeclaration(container) || getContextualThisParameterType(container);
                 if (thisType) {
                     return thisType;
                 }