diff --git a/Dockerfile-postgres b/Dockerfile-postgres
index 1d3f67c..9a681bc 100644
--- a/Dockerfile-postgres
+++ b/Dockerfile-postgres
@@ -1,5 +1,6 @@
 # Versions must be major.minor
 # Default versions are as below
+# RUST_VERSION should match the MSRV in Cargo.toml.
 ARG RUST_VERSION=1.88
 ARG ALPINE_VERSION=3.20
 
diff --git a/Dockerfile-sqlite b/Dockerfile-sqlite
index cf72694..8457eb5 100644
--- a/Dockerfile-sqlite
+++ b/Dockerfile-sqlite
@@ -1,5 +1,6 @@
 # Versions must be major.minor
 # Default versions are as below
+# RUST_VERSION should match the MSRV in Cargo.toml.
 ARG RUST_VERSION=1.88
 ARG ALPINE_VERSION=3.20