diff --git a/install.sh b/install.sh
index 12f5190..e23151a 100644
--- a/install.sh
+++ b/install.sh
@@ -126,7 +126,7 @@ ensure_node_runtime() {
 
   if have_cmd node && have_cmd npm; then
     major="$(node_major)"
-    if [[ -n "${major}" && "${major}" -ge 18 ]]; then
+    if [[ -n "${major}" && "${major}" -ge 20 ]]; then
       return 0
     fi
   fi
@@ -137,10 +137,20 @@ ensure_node_runtime() {
       install_with_manager "${manager}" node
       ;;
     apt-get)
-      install_with_manager "${manager}" nodejs npm
+      log "Adding NodeSource LTS repository..."
+      if ! curl -fsSL https://deb.nodesource.com/setup_lts.x | sudo -E bash -; then
+        echo "Failed to set up NodeSource repository for Node.js." >&2
+        exit 1
+      fi
+      install_with_manager "${manager}" nodejs
       ;;
     dnf|yum)
-      install_with_manager "${manager}" nodejs npm
+      log "Adding NodeSource LTS repository..."
+      if ! curl -fsSL https://rpm.nodesource.com/setup_lts.x | sudo -E bash -; then
+        echo "Failed to set up NodeSource repository for Node.js." >&2
+        exit 1
+      fi
+      install_with_manager "${manager}" nodejs
       ;;
     *)
       echo "No supported package manager available to install Node.js." >&2
@@ -154,8 +164,8 @@ ensure_node_runtime() {
   fi
 
   major="$(node_major)"
-  if [[ -z "${major}" || "${major}" -lt 18 ]]; then
-    echo "suitup requires Node.js 18 or later. Installed version is $(node -v)." >&2
+  if [[ -z "${major}" || "${major}" -lt 20 ]]; then
+    echo "suitup requires Node.js 20 or later. Installed version is $(node -v)." >&2
     exit 1
   fi
 }
@@ -177,7 +187,7 @@ require_cmd uname
 
 PACKAGE_MANAGER="$(detect_package_manager || true)"
 if [[ -z "${PACKAGE_MANAGER}" ]]; then
-  echo "Could not detect a supported package manager. Install zsh and Node.js 18+ manually, then rerun suitup." >&2
+  echo "Could not detect a supported package manager. Install zsh and Node.js 20+ manually, then rerun suitup." >&2
   exit 1
 fi
 
diff --git a/tests/install-script.test.js b/tests/install-script.test.js
index 35eee5c..440b72f 100644
--- a/tests/install-script.test.js
+++ b/tests/install-script.test.js
@@ -47,4 +47,22 @@ describe("install.sh", () => {
 
     expect(content).toContain('Unknown command: ${CLI_COMMAND}');
   });
+
+  test("skips Node.js installation when a compatible version is already present", () => {
+    const content = readFileSync(INSTALL_SCRIPT, "utf-8");
+
+    // ensure_node_runtime returns early when node + npm are found at version >= 20
+    expect(content).toContain("if have_cmd node && have_cmd npm;");
+    expect(content).toMatch(/"\$\{major\}" -ge 20/);
+    expect(content).toContain("return 0");
+  });
+
+  test("uses NodeSource repository for reliable Node.js installation on Linux", () => {
+    const content = readFileSync(INSTALL_SCRIPT, "utf-8");
+
+    expect(content).toContain("https://deb.nodesource.com/setup_lts.x");
+    expect(content).toContain("https://rpm.nodesource.com/setup_lts.x");
+    // NodeSource setup scripts are piped into bash with sudo
+    expect(content).toMatch(/curl.*nodesource.*\| sudo -E bash -/s);
+  });
 });