diff --git a/scripts/install-cli.sh b/scripts/install-cli.sh
index bc964ca9743e..397d35ef250f 100755
--- a/scripts/install-cli.sh
+++ b/scripts/install-cli.sh
@@ -255,19 +255,31 @@ parse_args() {
         shift
         ;;
       --prefix)
+        if [[ $# -lt 2 || "${2:-}" == --* ]]; then
+          fail "Missing value for $1"
+        fi
         PREFIX="$2"
         shift 2
         ;;
       --version)
+        if [[ $# -lt 2 || "${2:-}" == --* ]]; then
+          fail "Missing value for $1"
+        fi
         OPENCLAW_VERSION="$2"
         shift 2
         ;;
       --node-version)
+        if [[ $# -lt 2 || "${2:-}" == --* ]]; then
+          fail "Missing value for $1"
+        fi
         NODE_VERSION="$2"
         NODE_VERSION_REQUESTED=1
         shift 2
         ;;
       --install-method|--method)
+        if [[ $# -lt 2 || "${2:-}" == --* ]]; then
+          fail "Missing value for $1"
+        fi
         INSTALL_METHOD="$2"
         shift 2
         ;;
@@ -280,6 +292,9 @@ parse_args() {
         shift
         ;;
       --git-dir|--dir)
+        if [[ $# -lt 2 || "${2:-}" == --* ]]; then
+          fail "Missing value for $1"
+        fi
         GIT_DIR="$2"
         shift 2
         ;;
diff --git a/scripts/install.sh b/scripts/install.sh
index 44d430d4206e..a417bff39bf4 100755
--- a/scripts/install.sh
+++ b/scripts/install.sh
@@ -1232,10 +1232,18 @@ parse_args() {
                 shift
                 ;;
             --install-method|--method)
+                if [[ $# -lt 2 || "${2:-}" == --* ]]; then
+                    ui_error "Missing value for $1"
+                    return 2
+                fi
                 INSTALL_METHOD="$2"
                 shift 2
                 ;;
             --version)
+                if [[ $# -lt 2 || "${2:-}" == --* ]]; then
+                    ui_error "Missing value for $1"
+                    return 2
+                fi
                 OPENCLAW_VERSION="$2"
                 shift 2
                 ;;
@@ -1252,6 +1260,10 @@ parse_args() {
                 shift
                 ;;
             --git-dir|--dir)
+                if [[ $# -lt 2 || "${2:-}" == --* ]]; then
+                    ui_error "Missing value for $1"
+                    return 2
+                fi
                 GIT_DIR="$2"
                 shift 2
                 ;;
@@ -1260,7 +1272,8 @@ parse_args() {
                 shift
                 ;;
             *)
-                shift
+                ui_error "Unknown option: $1"
+                return 2
                 ;;
         esac
     done
diff --git a/test/scripts/install-cli.test.ts b/test/scripts/install-cli.test.ts
index 40bf2dd6a1bd..cfebf359c8be 100644
--- a/test/scripts/install-cli.test.ts
+++ b/test/scripts/install-cli.test.ts
@@ -104,6 +104,18 @@ function writeNpmBeforePolicyFixture(path: string, argsLog: string) {
 describe("install-cli.sh", () => {
   const script = readFileSync(SCRIPT_PATH, "utf8");
 
+  it("rejects installer options with missing values", () => {
+    const result = runInstallCliShell(`
+      set -euo pipefail
+      source "${SCRIPT_PATH}"
+      parse_args --prefix --no-onboard
+    `);
+
+    expect(result.status).toBe(1);
+    expect(result.stdout + result.stderr).toContain("Missing value for --prefix");
+    expect(result.stdout + result.stderr).not.toContain("unbound variable");
+  });
+
   it("keeps HOME for default prefix while OPENCLAW_HOME controls git checkout paths", () => {
     const tmp = mkdtempSync(join(tmpdir(), "openclaw-install-cli-home-"));
     const osHome = join(tmp, "os-home");
diff --git a/test/scripts/install-sh.test.ts b/test/scripts/install-sh.test.ts
index a9f984dd74c3..aba98c017aab 100644
--- a/test/scripts/install-sh.test.ts
+++ b/test/scripts/install-sh.test.ts
@@ -102,6 +102,28 @@ describe("install.sh", () => {
     expect(rawAptInstalls).toStrictEqual([]);
   });
 
+  it("rejects unknown installer options", () => {
+    const result = runInstallShell(`
+      set -euo pipefail
+      source "${SCRIPT_PATH}"
+      parse_args --bogus
+    `);
+
+    expect(result.status).toBe(2);
+    expect(result.stdout + result.stderr).toContain("Unknown option: --bogus");
+  });
+
+  it("rejects installer options with missing values", () => {
+    const result = runInstallShell(`
+      set -euo pipefail
+      source "${SCRIPT_PATH}"
+      parse_args --version --no-onboard
+    `);
+
+    expect(result.status).toBe(2);
+    expect(result.stdout + result.stderr).toContain("Missing value for --version");
+  });
+
   it("accepts GNU and musl Linux shells in OS detection", () => {
     expect(script).toContain('[[ "$OSTYPE" == "linux"* ]]');
     expect(script).not.toContain('[[ "$OSTYPE" == "linux-gnu"* ]]');