diff --git a/Makefile b/Makefile
index 246b8f6..1fd0516 100644
--- a/Makefile
+++ b/Makefile
@@ -9,4 +9,4 @@ check-format:
 	dhall type --file package-set.dhall;
 	@echo checked dhall files are well-typed.
 ci: check-format
-	vessel verify --version 0.13.0
+	vessel verify --version 0.13.1
diff --git a/index/base.dhall b/index/base.dhall
index 8a76024..119ac07 100644
--- a/index/base.dhall
+++ b/index/base.dhall
@@ -5,6 +5,6 @@
 , authors = [ "DFINITY Languages Team" ]
 , owners = [ "dfinity" ]
 , repo = "https://github.com/dfinity/motoko-base.git"
-, version = "149ef18f92ea71f77751da84fb988359399a3050"
+, version = "38ec6d3ce517131482ebc96774d885591867092c"
 , dependencies = [] : List Text
 }