diff --git a/wai/quickstart/install.sh b/wai/quickstart/install.sh
index 31851f50f..c4f95c253 100755
--- a/wai/quickstart/install.sh
+++ b/wai/quickstart/install.sh
@@ -8,7 +8,7 @@
 # share/wai/web/ side by side. Then it says which line puts ~/.wai/bin on your PATH. Nothing
 # else is changed. WAI_VERSION picks a release (default: the one below).
 set -eu
-VERSION="${WAI_VERSION:-0.3.0}"
+VERSION="${WAI_VERSION:-0.4.0}"
 DEST="${WAI_HOME:-$HOME/.wai}"
 BASE="https://git.transaction.science/Transaction-Science/open-standards/releases/download/wai-v$VERSION"
 case "$(uname -s)" in