diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8b8694d..7057bc5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [3.40.0] - 2024-10-29
+
+### Fixed
+    - Cleaned legacy notation for ENV instruction
+    - Bump Flex and Stax SDK versions
+
 ## [3.39.0] - 2024-10-18
 
 ### Changed
diff --git a/legacy/Dockerfile b/legacy/Dockerfile
index 2ce5a10..6e7608a 100644
--- a/legacy/Dockerfile
+++ b/legacy/Dockerfile
@@ -1,7 +1,7 @@
 FROM ghcr.io/ledgerhq/ledger-app-builder/ledger-app-builder-lite:latest AS LITE_BUILDER
 
 FROM ubuntu:22.04
-ENV LANG C.UTF-8
+ENV LANG=C.UTF-8
 
 ARG DEBIAN_FRONTEND=noninteractive
 
@@ -39,7 +39,7 @@ RUN cd /usr/bin && \
 
 # ARM Embedded Toolchain
 # Integrity is checked using the MD5 checksum provided by ARM at https://developer.arm.com/tools-and-software/open-source-software/developer-tools/gnu-toolchain/gnu-rm/downloads
-ENV TOOLCHAIN_VERSION 10.3-2021.10
+ENV TOOLCHAIN_VERSION=10.3-2021.10
 RUN case $(uname -m) in \
         x86_64 | amd64) \
             ARCH=x86_64 \
diff --git a/lite/Dockerfile b/lite/Dockerfile
index f4d447b..cbaf745 100644
--- a/lite/Dockerfile
+++ b/lite/Dockerfile
@@ -1,5 +1,5 @@
 FROM alpine:3.15
-ENV LANG C.UTF-8
+ENV LANG=C.UTF-8
 
 RUN apk update
 RUN apk upgrade
@@ -88,12 +88,12 @@ RUN echo nanos2 > $NANOSP_SDK/.target
 
 # Latest Stax SDK (OS stax_1.5.0 => based on API_LEVEL 21)
 ENV STAX_SDK=/opt/stax-secure-sdk
-RUN git -C "$LEDGER_SECURE_SDK" worktree add "$STAX_SDK" v21.3.6
+RUN git -C "$LEDGER_SECURE_SDK" worktree add "$STAX_SDK" v21.3.7
 RUN echo stax > $STAX_SDK/.target
 
 # Latest Flex SDK (OS flex_1.1.1 => based on API_LEVEL 21)
 ENV FLEX_SDK=/opt/flex-secure-sdk
-RUN git -C "$LEDGER_SECURE_SDK" worktree add "$FLEX_SDK" v21.3.6
+RUN git -C "$LEDGER_SECURE_SDK" worktree add "$FLEX_SDK" v21.3.7
 RUN echo flex > $FLEX_SDK/.target
 
 # Default SDK