diff --git a/.forgejo/workflows/integration.yml b/.forgejo/workflows/integration.yml
index a7594d2..3246eef 100644
--- a/.forgejo/workflows/integration.yml
+++ b/.forgejo/workflows/integration.yml
@@ -8,6 +8,14 @@ jobs:
           set -x
           LXC_IP_PREFIX=10.0.9 ./forgejo-dependencies.sh
           ./forgejo.sh setup root admin1234 codeberg.org/forgejo/forgejo:1.19
+          #
+          # Uncomment the following for a shortcut to debugging the Forgejo runner.
+          # It will build the runner from a designated repository and branch instead of
+          # downloading it from a canonical release.
+          #
+          # ./forgejo-test-helper.sh build_runner http://code.forgejo.org/forgejo/runner branch-under-debug
+          # export PATH=$(pwd)/forgejo-runner:$PATH
+          #
           ./forgejo-runner.sh setup
           export FORGEJO_RUNNER_LOGS=forgejo-runner.log
           ./forgejo-test-helper.sh run_workflow testdata/demo http://root:admin1234@$(cat forgejo-ip):3000 root demo setup-forgejo $(cat forgejo-token) > /tmp/output
diff --git a/action.yml b/action.yml
index e765be3..eae3f42 100644
--- a/action.yml
+++ b/action.yml
@@ -21,6 +21,11 @@ description: |
     Create the repository `$forgejo/root/testrepo` and populate it with the
     content of the `testrepo` directory. The SHA of the tip of the repository
     is in the output, starting with `sha=`.
+  * `forgejo-test-helper.sh build_runner $forgejo/forgejo/runner v1.4.1`
+    Builds the forgejo runner from source in `./forgejo-runner/forgejo-runner`.
+    `export PATH=$(pwd)/forgejo-runner:$PATH` will ensure that calling `forgejo-runner.sh`
+    will use this binary instead of downloading a released version of the runner.
+    If the version is not specified, build from the main branch.
 
   The combination of `push_self_action` and `run_workflow` allows to
   run Forgejo Actions workflows from `testrepo` that use the action
diff --git a/forgejo-runner.sh b/forgejo-runner.sh
index 16b8236..b52575b 100755
--- a/forgejo-runner.sh
+++ b/forgejo-runner.sh
@@ -13,18 +13,21 @@ function download() {
     local runner_repository="$1"
     local version="$2"
 
-    curl -L --fail -sS $runner_repository/releases/download/$version/forgejo-runner-amd64 > /bin/forgejo-runner
-    chmod 755 /bin/forgejo-runner
+    if ! which forgejo-runner > /dev/null; then
+	curl -L --fail -sS $runner_repository/releases/download/$version/forgejo-runner-amd64 > /bin/forgejo-runner
+	chmod 755 /bin/forgejo-runner
+    fi
 }
 
 function register() {
     local forgejo="$1"
     docker exec --user 1000 forgejo forgejo actions --registration-token-admin > forgejo-runner-token
-    timeout --signal=KILL 30 forgejo-runner register --no-interactive --instance "$forgejo" --name runner --token $(cat forgejo-runner-token) --labels ubuntu-latest:docker://node:16-buster,self-hosted    
+    timeout --signal=KILL 30 forgejo-runner register --no-interactive --instance "$forgejo" --name runner --token $(cat forgejo-runner-token) --labels ubuntu-latest:docker://node:16-buster,self-hosted
 }
 
 function run() {
-    daemon --chdir=$(pwd) --unsafe --pidfile=$(pwd)/forgejo-runner-pid --errlog=$(pwd)/forgejo-runner.log --output=$(pwd)/forgejo-runner.log /bin/forgejo-runner daemon
+    rm -f forgejo-runner.log
+    daemon --chdir=$(pwd) --unsafe --pidfile=$(pwd)/forgejo-runner-pid --errlog=$(pwd)/forgejo-runner.log --output=$(pwd)/forgejo-runner.log forgejo-runner daemon
     sleep 1
     cat forgejo-runner.log
 }    
diff --git a/forgejo-test-helper.sh b/forgejo-test-helper.sh
index 386602d..ebc53c9 100755
--- a/forgejo-test-helper.sh
+++ b/forgejo-test-helper.sh
@@ -9,6 +9,37 @@ DIR=$(mktemp -d)
 
 trap "rm -fr $DIR" EXIT
 
+function dependency_go() {
+    if ! which go > /dev/null ; then
+	apt-get update
+        apt-get install -y -qq wget tar
+        wget https://go.dev/dl/go1.20.3.linux-amd64.tar.gz
+        tar zxf go1.20.3.linux-amd64.tar.gz
+        export PATH=$PATH:$(pwd)/go/bin
+    fi
+}
+
+function checkout() {
+    local git="$1"
+    rm -fr forgejo-runner
+    git clone $git forgejo-runner
+}
+
+function build_runner() {
+    local git="$1"
+    local version="${2:-main}"
+
+    (
+	checkout "$git"
+	dependency_go
+	cd forgejo-runner
+	git checkout "$version"
+	make build
+    )
+    export PATH=$PATH:$(pwd)/forgejo-runner
+    forgejo-runner --version
+}
+
 function api() {
     method=$1
     shift