diff --git a/hidpi.sh b/hidpi.sh
index 4d2c406..47acdd3 100755
--- a/hidpi.sh
+++ b/hidpi.sh
@@ -102,7 +102,7 @@ function get_edid() {
             let index++
             MonitorName=("$(echo ${display:190:24} | xxd -p -r)")
             VendorID=${display:16:4}
-            ProductID=${gMonitor:22:2}${gMonitor:20:2}
+            ProductID=${display:22:2}${display:20:2}
 
             if [[ ${VendorID} == 0610 ]]; then
                 MonitorName="Apple Display"
@@ -197,7 +197,7 @@ function get_edid() {
         echo '------------------------------------'
         for display in "${gDisplayInf[@]}"; do
             let index++
-            printf "    %d    |    ${display:16:4}    |    ${gMonitor:22:2}${gMonitor:20:2}\n" $index
+            printf "    %d    |    ${display:16:4}    |    ${display:22:2}${display:20:2}\n" $index
         done
         echo '------------------------------------'
         read -p "Choose the display: " selection