diff --git a/doc.zih.tu-dresden.de/util/check-spelling.sh b/doc.zih.tu-dresden.de/util/check-spelling.sh
index b58e4897e19162ed6490d8ef63c10779cc3187da..27f10a8e2078f9d020a8366847fa4e4169eddee0 100755
--- a/doc.zih.tu-dresden.de/util/check-spelling.sh
+++ b/doc.zih.tu-dresden.de/util/check-spelling.sh
@@ -40,7 +40,8 @@ function is_wordlist_sorted(){
 }
 
 function should_skip_file(){
-  local result="$(git check-attr check-spelling -- "$1")"
+  local result
+  result="$(git check-attr check-spelling -- "$1")"
   test "${result#*: check-spelling: }" = "unset"
 }
 
@@ -83,7 +84,12 @@ function is_mistake_count_increased_by_changes(){
 
   source_hash=`git merge-base HEAD "${branch}"`
   #Remove everything except lines beginning with --- or +++
-  files=`git diff ${source_hash} -- '*.md' | sed -E -n 's#^(---|\+\+\+) ((/|./)[^[:space:]]+)$#\2#p'`
+  files=$(git diff ${source_hash} -- '*.md' \
+    | sed -E -n 's#^(---|\+\+\+) ((/|./)[^[:space:]]+)$#\2#p')
+  #Special case: when ${files} is empty, we need to prevent the failure at 'read newfile'
+  if [[ -z "${files}" ]]; then
+    return 0
+  fi
   #echo "${files}"
   #echo "-------------------------"
   #Assume that we have pairs of lines (starting with --- and +++).
diff --git a/doc.zih.tu-dresden.de/util/download-newest-mermaid.js.sh b/doc.zih.tu-dresden.de/util/download-newest-mermaid.js.sh
index 5255c30aa7e4760cc356e4e704cb69ee35bc668f..2ea79b26c110d3f932c52b992da9dda0d0e01df7 100755
--- a/doc.zih.tu-dresden.de/util/download-newest-mermaid.js.sh
+++ b/doc.zih.tu-dresden.de/util/download-newest-mermaid.js.sh
@@ -6,4 +6,4 @@ scriptpath=${BASH_SOURCE[0]}
 basedir=`dirname "${scriptpath}"`
 basedir=`dirname "${basedir}"`
 cd ${basedir}/tud_theme/javascripts
-wget https://unpkg.com/mermaid@9.4.0/dist/mermaid.min.js
+wget https://unpkg.com/mermaid@11.4.1/dist/mermaid.min.js