diff --git a/.circleci/config.yml b/.circleci/config.yml
index a451e0f..5a98128 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -2,7 +2,7 @@ version: 2
 jobs:
   test:
     docker:
-      - image: circleci/rust:1.35-stretch
+      - image: circleci/rust:1.40-stretch
     working_directory: ~/repo
     steps:
       - checkout