diff --git a/README.md b/README.md
index 498e987..c375b86 100644
--- a/README.md
+++ b/README.md
@@ -14,12 +14,22 @@ jobs:
     steps:
       - uses: https://git.kemitix.net/kemitix/rust@v1.80.0
         with:
-          args: cargo test
+          args: nightly cargo test
       - uses: https://git.kemitix.net/kemitix/rust@v1.80.0
         with:
-          args: cargo build
+          args: v1.79.0 cargo build
 ```
 
+The `args` is one of the following:
+
+- <COMMAND>
+- [ [nightly | stable | v1.xx.x] ] <COMMAND>
+
+`COMMAND` is the command you want to run. The optional prefix is the Rust toolchain, or version. Allowed values are `nightly`, `stable` or a Rust version.
+
+Where the optional prefix is not given, the `stable` toolchain will be used.
+
+
 ## Contents
 
 - nodejs
diff --git a/entrypoint.sh b/entrypoint.sh
index 284c41a..de787ef 100755
--- a/entrypoint.sh
+++ b/entrypoint.sh
@@ -2,5 +2,46 @@
 
 set -e
 
-rustup update
-${INPUT_ARGS}
+echo "INPUT_ARGS: ${INPUT_ARGS}"
+
+# split input into an array
+read -ra ARGS <<<"${INPUT_ARGS}"
+
+# default toolchain
+TOOLCHAIN="stable"
+echo "Default toolchain: ${TOOLCHAIN}"
+
+# if first parameter is 'nightly'...
+if test "${ARGS[0]}" == "nightly"; then
+  TOOLCHAIN="nightly"
+  ARGS=("${ARGS[@]:1}")
+fi
+if test "${ARGS[0]}" == "stable"; then
+  TOOLCHAIN="stable" # redundant as this is the default
+  ARGS=("${ARGS[@]:1}")
+fi
+if [[ "${ARGS[0]}" == v1* ]]; then
+  TOOLCHAIN="${ARGS[0]:1}"
+  ARGS=("${ARGS[@]:1}")
+fi
+echo "Selected toolchain: ${TOOLCHAIN}"
+
+rustup update "${TOOLCHAIN}"
+
+if test "${ARGS[0]}" == "cargo";then
+  PRE_COMMAND="cargo +${TOOLCHAIN} "
+else
+  PRE_COMMAND="${ARGS[0]}"
+fi
+ARGS=("${ARGS[@]:1}")
+
+# ensure toolchain is up-to-date
+# recombine remaining arguments
+COMMAND=$(
+  IFS=" "
+  echo "${ARGS[*]}"
+)
+
+# execute command
+echo "${PRE_COMMAND} ${COMMAND}"
+${PRE_COMMAND} ${COMMAND}