diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 888b07f..c0dff4e 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -105,7 +105,7 @@ jobs:
         rust:
           - stable
           - beta
-          - 1.38.0
+          - 1.40.0
         os:
           - ubuntu-latest
           - macos-latest
diff --git a/CHANGELOG.markdown b/CHANGELOG.markdown
index 93cf305..74e4639 100644
--- a/CHANGELOG.markdown
+++ b/CHANGELOG.markdown
@@ -5,6 +5,7 @@
 ### Changed
 
 - Redesigned tree / collapsing header API
+- Bump minimum Rust version to 1.40 (at least xml-rs crate requires it)
 
 ## [0.3.1] - 2020-03-16
 
diff --git a/README.markdown b/README.markdown
index 7186677..2b4e662 100644
--- a/README.markdown
+++ b/README.markdown
@@ -2,7 +2,7 @@
 
 **Still fairly experimental!**
 
-Minimum Rust version: 1.38
+Minimum Rust version: 1.40
 
 Wrapped Dear ImGui version: 1.75