diff --git a/data_from_portwine/scripts/functions_helper b/data_from_portwine/scripts/functions_helper
index 3b82c74..e49b8b4 100755
--- a/data_from_portwine/scripts/functions_helper
+++ b/data_from_portwine/scripts/functions_helper
@@ -3644,7 +3644,9 @@ fi
     YAD_MH_FPS_LIMIT=$(<"${PORT_WINE_TMP_PATH}/tmp_yad_mh_fps_limit")
 
     MONITOR_HEIGHT="$(echo $PW_SCREEN_RESOLUTION | awk -F'x' '{print $2}')"
-    MH_FONT_SIZE="font_size=$(( MONITOR_HEIGHT / 45 ))"
+    if [[ ! -z "$MONITOR_HEIGHT" ]]
+    then MH_FONT_SIZE="font_size=$(( MONITOR_HEIGHT / 45 ))"
+    fi
 
     local INT_COUNT_MH=0
     for read_list_mh in ${YAD_MH_SET} ; do