diff --git a/.github/workflows/batch-check.yaml b/.github/workflows/batch-check.yaml
index 79256ac0..1cb921ac 100644
--- a/.github/workflows/batch-check.yaml
+++ b/.github/workflows/batch-check.yaml
@@ -152,34 +152,18 @@ jobs:
           cpanm Unicode::GCString
           cpanm --force Win32::Unicode::File
           cpanm --force Win32::API
-      - name: rebuild and install PAR-Packer-master
-      #If the version number of PAR::Packer does not exceed 1.061, it is necessary to rebuild and install PAR-Packer-master
-      #https://github.com/rschupp/PAR-Packer/issues/84
-      #Issue #84: pass UTF-16 command line down to my_perl (using _wspawnvp)
-        run: |
-          Invoke-WebRequest -Uri https://github.com/rschupp/PAR-Packer/archive/refs/heads/master.zip -OutFile PAR-Packer-master.zip
-          unzip PAR-Packer-master.zip
-          cd PAR-Packer-master
-          perl Makefile.PL
-          gmake
-          gmake install
       - name: preparations for PAR packer
         run: |
           sed -i'.bak' -r 's,eval\s\"use\sUnicode::GCString\"\sif\s\$switches\{GCString\},use Unicode::GCString,' latexindent.pl
-          SET PAR_VERBATIM=1
       #
       # https://metacpan.org/pod/pp
       # https://github.com/plk/biber/blob/dev/dist/MSWIN64/build.bat
       #
       - name: create latexindent.exe using PAR Packer
-        run: >-
-          pp
-          -T
-          -M Win32::Unicode
-          --addfile="defaultSettings.yaml;lib/LatexIndent/defaultSettings.yaml"
-          --cachedeps=scancache
-          --output latexindent.exe
-          latexindent.pl
+        shell: cmd
+        run: |
+          set PAR_VERBATIM=1
+          pp -M Win32::Unicode --addfile="defaultSettings.yaml;lib/LatexIndent/defaultSettings.yaml" --cachedeps=scancache --output latexindent.exe latexindent.pl
       - name: latexindent.exe help
         run: |
           ./latexindent.exe --help
@@ -204,3 +188,8 @@ jobs:
           cat test-cases/back-up-tests/indent.log
           ./latexindent.exe test-cases/back-up-tests/新建äö.tex -g="新建äö.log" -c="D:/新建"
           cat D:/新建/新建äö.log
+      - name: latexindent.exe -GCString test, issue 531
+        # https://github.com/cmhughes/latexindent.pl/issues/531
+        run: |
+          ./latexindent.exe test-cases/GCString-test/GCString.tex -y="defaultIndent: '    '" -GCString -o=++
+          cat test-cases/GCString-test/indent.log
\ No newline at end of file
diff --git a/.github/workflows/build-documentation-and-executables.yaml b/.github/workflows/build-documentation-and-executables.yaml
index 0ce31182..cc58cf16 100644
--- a/.github/workflows/build-documentation-and-executables.yaml
+++ b/.github/workflows/build-documentation-and-executables.yaml
@@ -88,34 +88,18 @@ jobs:
           cpanm Unicode::GCString
           cpanm --force Win32::Unicode::File
           cpanm --force Win32::API
-      - name: rebuild and install PAR-Packer-master
-      #If the version number of PAR::Packer does not exceed 1.061, it is necessary to rebuild and install PAR-Packer-master
-      #https://github.com/rschupp/PAR-Packer/issues/84
-      #Issue #84: pass UTF-16 command line down to my_perl (using _wspawnvp)
-        run: |
-          Invoke-WebRequest -Uri https://github.com/rschupp/PAR-Packer/archive/refs/heads/master.zip -OutFile PAR-Packer-master.zip
-          unzip PAR-Packer-master.zip
-          cd PAR-Packer-master
-          perl Makefile.PL
-          gmake
-          gmake install
       - name: preparations for PAR packer
         run: |
           sed -i'.bak' -r 's,eval\s\"use\sUnicode::GCString\"\sif\s\$switches\{GCString\},use Unicode::GCString,' latexindent.pl
-          SET PAR_VERBATIM=1
       #
       # https://metacpan.org/pod/pp
       # https://github.com/plk/biber/blob/dev/dist/MSWIN64/build.bat
       #
       - name: create latexindent.exe using PAR Packer
-        run: >-
-          pp
-          -T
-          -M Win32::Unicode
-          --addfile="defaultSettings.yaml;lib/LatexIndent/defaultSettings.yaml"
-          --cachedeps=scancache
-          --output latexindent.exe
-          latexindent.pl
+        shell: cmd
+        run: |
+          set PAR_VERBATIM=1
+          pp -M Win32::Unicode --addfile="defaultSettings.yaml;lib/LatexIndent/defaultSettings.yaml" --cachedeps=scancache --output latexindent.exe latexindent.pl
       - name: move latexindent.exe to release directory
         run: |
           mkdir -p target/release
diff --git a/test-cases/GCString-test/GCString.tex b/test-cases/GCString-test/GCString.tex
new file mode 100644
index 00000000..568e13e6
--- /dev/null
+++ b/test-cases/GCString-test/GCString.tex
@@ -0,0 +1,13 @@
+\begin{table}[H]
+  \centering
+  \begin{tblr}{
+      hlines,
+      vlines,
+      cells = {c,m}}
+    5:30        & 起床 & 12:30～14:00 & 午休  \\
+    6:00～7:00   & 早操 & 14:00～17:30 & 集训  \\
+    7:00～7:50   & 早餐 & 17:30～18:30 & 晚餐  \\
+    7:50～11:00  & 集训 & 19:00～21:00 & 晚自习 \\
+    11:00～12:30 & 午餐 & 23:00       & 熄灯  \\
+  \end{tblr}
+\end{table}
\ No newline at end of file