--- a/taskcluster/docker/funsize-update-generator/scripts/mbsdiff_hook.sh
+++ b/taskcluster/docker/funsize-update-generator/scripts/mbsdiff_hook.sh
@@ -57,17 +57,17 @@ print_usage(){
     echo "-u post hook - upload patch to cache for future use"
     echo ""
     echo "PATH-FROM-URL     : path on disk for source file"
     echo "PATH-TO-URL       : path on disk for destination file"
     echo "PATH-PATCH        : path on disk for patch between source and destination"
 }
 
 upload_patch(){
-    if [ "$(stat -f "%z" "$2")" -lt ${CACHE_THRESHOLD} ]
+    if [ "$(stat -c "%s" "$2")" -lt ${CACHE_THRESHOLD} ]
     then
       return 0
     fi
     sha_from=$(getsha512 "$1")
     sha_to=$(getsha512 "$2")
     patch_path="$3"
     patch_filename="$(basename "$3")"
 
@@ -89,17 +89,17 @@ upload_patch(){
         echo "${patch_path} failed to be uploaded to s3://${AWS_BUCKET_NAME}"
         return 1
     fi
     return 0
 }
 
 get_patch(){
     # $1 and $2 are the /path/to/filename
-    if [ "$(stat -f "%z" "$2")" -lt ${CACHE_THRESHOLD} ]
+    if [ "$(stat -c "%s" "$2")" -lt ${CACHE_THRESHOLD} ]
     then
       return 1
     fi
     sha_from=$(getsha512 "$1")
     sha_to=$(getsha512 "$2")
     destination_file="$3"
     s3_filename="$(basename "$3")"