diff --git a/src/install.sh b/src/install.sh
index ddaff1a..558b10e 100644
--- a/src/install.sh
+++ b/src/install.sh
@@ -147,7 +147,7 @@ finishInstall() {
         fi
       fi
       # Enable secure boot on multi-socket systems to workaround freeze
-      if [[ "$SOCKETS" != "1" ]]; then
+      if [ -n "$SOCKETS" ] && [[ "$SOCKETS" != "1" ]]; then
         BOOT_MODE="windows_secure"
         echo "$BOOT_MODE" > "$STORAGE/windows.mode"    
       fi