diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 3c5563b..f6c6790 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -72,6 +72,11 @@ jobs:
           cargo test --workspace
           cargo test -p lla --features wasm-plugins
 
+      - name: Test Unix installer
+        if: runner.os != 'Windows'
+        shell: bash
+        run: ./scripts/test_install_sh.sh
+
       - name: Compile SDK fixtures
         run: |
           cargo check --manifest-path sdk/tests/fixtures/minimal_native/Cargo.toml
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2156abf..63d92cb 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 
+- The Unix installer can once again be executed through the documented
+  `curl ... | bash` command without an unset `BASH_SOURCE` error.
 - The Windows installer now handles GitHub checksum manifests correctly in
   Windows PowerShell 5.1 and avoids its legacy Internet Explorer parsing prompt.
 
diff --git a/install.sh b/install.sh
index 9347a5b..0f58b57 100755
--- a/install.sh
+++ b/install.sh
@@ -166,6 +166,6 @@ main() {
     install_binary
 }
 
-if [[ "${BASH_SOURCE[0]}" == "$0" ]]; then
+if [[ -z "${BASH_SOURCE[0]:-}" || "${BASH_SOURCE[0]}" == "$0" ]]; then
     main "$@"
 fi
diff --git a/scripts/test_install_sh.sh b/scripts/test_install_sh.sh
new file mode 100755
index 0000000..45f49a5
--- /dev/null
+++ b/scripts/test_install_sh.sh
@@ -0,0 +1,101 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+repo_root="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+test_dir="$(mktemp -d)"
+trap 'rm -rf "$test_dir"' EXIT
+
+mkdir -p "$test_dir/bin"
+
+cat >"$test_dir/bin/uname" <<'EOF'
+#!/usr/bin/env bash
+case "${1:-}" in
+    -s) printf '%s\n' Linux ;;
+    -m) printf '%s\n' x86_64 ;;
+    *) exit 1 ;;
+esac
+EOF
+
+cat >"$test_dir/bin/curl" <<'EOF'
+#!/usr/bin/env bash
+set -euo pipefail
+
+output=""
+url=""
+while (( $# > 0 )); do
+    case "$1" in
+        -o)
+            output="$2"
+            shift 2
+            ;;
+        http://*|https://*)
+            url="$1"
+            shift
+            ;;
+        *)
+            shift
+            ;;
+    esac
+done
+
+case "$url" in
+    */releases/latest)
+        printf '%s\n' '{"tag_name":"v0.0.0-test"}'
+        ;;
+    */SHA256SUMS)
+        printf '%s  %s\n' "$MOCK_SHA256" lla-linux-amd64 >"$output"
+        ;;
+    */lla-linux-amd64)
+        printf '%s\n' 'fake lla binary' >"$output"
+        ;;
+    *)
+        printf 'Unexpected curl URL: %s\n' "$url" >&2
+        exit 1
+        ;;
+esac
+EOF
+
+cat >"$test_dir/bin/sudo" <<'EOF'
+#!/usr/bin/env bash
+printf '%s\n' "$*" >>"$MOCK_SUDO_LOG"
+EOF
+
+chmod +x "$test_dir/bin/uname" "$test_dir/bin/curl" "$test_dir/bin/sudo"
+
+if command -v sha256sum >/dev/null 2>&1; then
+    mock_sha256="$(printf '%s\n' 'fake lla binary' | sha256sum | awk '{print $1}')"
+else
+    mock_sha256="$(printf '%s\n' 'fake lla binary' | shasum -a 256 | awk '{print $1}')"
+fi
+
+run_installer() {
+    local mode="$1"
+    local output_file="$test_dir/${mode}.out"
+    local sudo_log="$test_dir/${mode}.sudo"
+
+    : >"$sudo_log"
+    if [[ "$mode" == direct ]]; then
+        PATH="$test_dir/bin:$PATH" \
+            MOCK_SHA256="$mock_sha256" \
+            MOCK_SUDO_LOG="$sudo_log" \
+            bash "$repo_root/install.sh" >"$output_file"
+    else
+        PATH="$test_dir/bin:$PATH" \
+            MOCK_SHA256="$mock_sha256" \
+            MOCK_SUDO_LOG="$sudo_log" \
+            bash -s -- <"$repo_root/install.sh" >"$output_file"
+    fi
+
+    grep -Fq 'lla v0.0.0-test has been installed successfully!' "$output_file"
+    grep -Fq 'mv ' "$sudo_log"
+}
+
+bash -n "$repo_root/install.sh"
+run_installer direct
+run_installer piped
+
+sourced_output="$(bash -c 'source "$1"; printf sourced' _ "$repo_root/install.sh")"
+[[ "$sourced_output" == sourced ]]
+
+printf '%s\n' 'install.sh tests passed'