diff --git a/README.md b/README.md
index d5e3774..864320b 100644
--- a/README.md
+++ b/README.md
@@ -21,6 +21,8 @@ A minimalist terminal chat server with Vim-style interface over SSH.
 ```sh
 curl -sSL https://raw.githubusercontent.com/m1ngsama/TNT/main/install.sh | sh
 ```
+The installer verifies the downloaded release binary against `checksums.txt`
+before installing it.
 
 **From source:**
 ```sh
diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index 3d8c3b8..41b9f98 100644
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -37,6 +37,8 @@
 - The tag-triggered release workflow now builds on native x64/arm64 runners,
   verifies artifact architecture, emits one checksum file, and creates a draft
   release for manual review instead of publishing immediately.
+- The one-line installer now downloads `checksums.txt`, verifies the selected
+  binary before installation, and fails fast on missing release assets.
 
 ## 2026-05-18 - Interactive input polish
 
diff --git a/install.sh b/install.sh
index 2935245..144b5c7 100755
--- a/install.sh
+++ b/install.sh
@@ -1,24 +1,51 @@
 #!/bin/sh
-# TNT Auto-deploy script
+# TNT installer
 # Usage: curl -sSL https://raw.githubusercontent.com/m1ngsama/TNT/main/install.sh | sh
 
 set -e
 
 VERSION=${VERSION:-latest}
 INSTALL_DIR=${INSTALL_DIR:-/usr/local/bin}
+REPO="m1ngsama/TNT"
+
+fail() {
+    echo "ERROR: $*" >&2
+    exit 1
+}
+
+need_cmd() {
+    command -v "$1" >/dev/null 2>&1 || fail "$1 is required"
+}
+
+sha256_of() {
+    if command -v sha256sum >/dev/null 2>&1; then
+        sha256sum "$1" | awk '{print $1}'
+    elif command -v shasum >/dev/null 2>&1; then
+        shasum -a 256 "$1" | awk '{print $1}'
+    else
+        return 1
+    fi
+}
+
+need_cmd curl
+need_cmd awk
 
 # Detect OS and architecture
 OS=$(uname -s | tr '[:upper:]' '[:lower:]')
 ARCH=$(uname -m)
 
+case "$OS" in
+    linux|darwin) ;;
+    *) fail "Unsupported OS: $OS" ;;
+esac
+
 case "$ARCH" in
     x86_64) ARCH="amd64" ;;
     aarch64|arm64) ARCH="arm64" ;;
-    *) echo "Unsupported architecture: $ARCH"; exit 1 ;;
+    *) fail "Unsupported architecture: $ARCH" ;;
 esac
 
 BINARY="tnt-${OS}-${ARCH}"
-REPO="m1ngsama/TNT"
 
 echo "=== TNT Installer ==="
 echo "OS: $OS"
@@ -29,34 +56,57 @@ echo ""
 # Get latest version if not specified
 if [ "$VERSION" = "latest" ]; then
     echo "Fetching latest version..."
-    VERSION=$(curl -sSL "https://api.github.com/repos/$REPO/releases/latest" | grep '"tag_name":' | sed -E 's/.*"([^"]+)".*/\1/')
+    VERSION=$(curl -fsSL "https://api.github.com/repos/$REPO/releases/latest" |
+        sed -n 's/.*"tag_name":[[:space:]]*"\([^"]*\)".*/\1/p' |
+        head -n 1)
+    [ -n "$VERSION" ] || fail "Could not determine latest release version"
 fi
 
 echo "Installing version: $VERSION"
 
 # Download
 URL="https://github.com/$REPO/releases/download/$VERSION/$BINARY"
+CHECKSUM_URL="https://github.com/$REPO/releases/download/$VERSION/checksums.txt"
 echo "Downloading from: $URL"
 
-TMP_FILE=$(mktemp)
-if ! curl -sSL -o "$TMP_FILE" "$URL"; then
-    echo "ERROR: Failed to download $BINARY"
-    rm -f "$TMP_FILE"
-    exit 1
-fi
+TMP_FILE=$(mktemp "${TMPDIR:-/tmp}/tnt.XXXXXX")
+CHECKSUM_FILE=$(mktemp "${TMPDIR:-/tmp}/tnt-checksums.XXXXXX")
+cleanup() {
+    rm -f "$TMP_FILE" "$CHECKSUM_FILE"
+}
+trap cleanup EXIT INT TERM
+
+curl -fsSL -o "$TMP_FILE" "$URL" || fail "Failed to download $BINARY"
+
+echo "Downloading checksums from: $CHECKSUM_URL"
+curl -fsSL -o "$CHECKSUM_FILE" "$CHECKSUM_URL" ||
+    fail "Failed to download checksums.txt"
+
+EXPECTED_SHA=$(awk -v name="$BINARY" '$2 == name { print $1; exit }' "$CHECKSUM_FILE")
+[ -n "$EXPECTED_SHA" ] || fail "No checksum entry found for $BINARY"
+
+ACTUAL_SHA=$(sha256_of "$TMP_FILE") ||
+    fail "sha256sum or shasum is required for checksum verification"
+
+[ "$ACTUAL_SHA" = "$EXPECTED_SHA" ] ||
+    fail "Checksum mismatch for $BINARY"
+
+echo "Checksum verified: $ACTUAL_SHA"
 
 # Install
 chmod +x "$TMP_FILE"
 
-if [ -w "$INSTALL_DIR" ]; then
-    mv "$TMP_FILE" "$INSTALL_DIR/tnt"
+if [ -d "$INSTALL_DIR" ] && [ -w "$INSTALL_DIR" ]; then
+    install -m 755 "$TMP_FILE" "$INSTALL_DIR/tnt"
 else
     echo "Need sudo for installation to $INSTALL_DIR"
-    sudo mv "$TMP_FILE" "$INSTALL_DIR/tnt"
+    need_cmd sudo
+    sudo mkdir -p "$INSTALL_DIR"
+    sudo install -m 755 "$TMP_FILE" "$INSTALL_DIR/tnt"
 fi
 
 echo ""
-echo "✓ TNT installed successfully to $INSTALL_DIR/tnt"
+echo "TNT installed successfully to $INSTALL_DIR/tnt"
 echo ""
 echo "Run with:"
 echo "  tnt"
diff --git a/scripts/release_check.sh b/scripts/release_check.sh
index aece2ff..06eec2c 100755
--- a/scripts/release_check.sh
+++ b/scripts/release_check.sh
@@ -14,6 +14,7 @@ Default checks:
   - clean build
   - unit tests
   - staged install layout with PREFIX=/usr and DESTDIR
+  - installer shell syntax
   - Arch/Homebrew packaging syntax
 
 Environment:
@@ -97,6 +98,9 @@ make DESTDIR="$tmpdir" PREFIX=/usr install-systemd
 [ -f "$tmpdir/usr/lib/systemd/system/tnt.service" ] ||
     fail "missing systemd unit: /usr/lib/systemd/system/tnt.service"
 
+step "checking installer syntax"
+sh -n install.sh
+
 step "checking packaging syntax"
 if command -v bash >/dev/null 2>&1; then
     bash -n packaging/arch/PKGBUILD