diff --git a/install.sh b/install.sh
index 87f12c6..641cf79 100644
--- a/install.sh
+++ b/install.sh
@@ -466,6 +466,7 @@ install_dependencies() {
         jq
         gnupg
         ca-certificates
+        lsb-release
     )
     
     for package in "${packages[@]}"; do
@@ -618,7 +619,10 @@ install_mullvad() {
     curl -fsSL https://mullvad.net/media/mullvad-code-signing.asc | gpg --dearmor -o /usr/share/keyrings/mullvad-keyring.gpg
     
     # Add Mullvad repository
-    echo "deb [signed-by=/usr/share/keyrings/mullvad-keyring.gpg arch=$( dpkg --print-architecture )] https://repository.mullvad.net/deb/stable $(lsb_release -cs) main" | tee /etc/apt/sources.list.d/mullvad.list
+    # Determine codename safely
+    CODENAME="$(lsb_release -cs 2>/dev/null || . /etc/os-release 2>/dev/null && echo "$VERSION_CODENAME")"
+    [ -z "$CODENAME" ] && CODENAME="stable"
+    echo "deb [signed-by=/usr/share/keyrings/mullvad-keyring.gpg arch=$( dpkg --print-architecture )] https://repository.mullvad.net/deb/stable $CODENAME main" | tee /etc/apt/sources.list.d/mullvad.list
     
     # Update and install
     apt-get update &>/dev/null