diff --git a/.github/workflows/integrationtest.yml b/.github/workflows/integrationtest.yml
index 325fd487..20b0ff88 100644
--- a/.github/workflows/integrationtest.yml
+++ b/.github/workflows/integrationtest.yml
@@ -134,15 +134,15 @@ jobs:
         uses: "ramsey/composer-install@v2"
         with:
           composer-options: '--optimize-autoloader'
-          # Bust the cache at least once a month - output format: YYYY-MM-DD.
-          custom-cache-suffix: $(date -u -d "-0 month -$(($(date +%d)-1)) days" "+%F")
+          # Bust the cache at least once a month - output format: YYYY-MM.
+          custom-cache-suffix: $(date -u "+%Y-%m")
 
       - name: Install Composer dependencies
         if: ${{ matrix.php == '8.3' }}
         uses: "ramsey/composer-install@v2"
         with:
           composer-options: '--ignore-platform-reqs --optimize-autoloader'
-          custom-cache-suffix: $(date -u -d "-0 month -$(($(date +%d)-1)) days" "+%F")
+          custom-cache-suffix: $(date -u "+%Y-%m")
 
       - name: Run integration tests
         run: vendor/bin/phpunit --no-coverage
diff --git a/.github/workflows/phplint.yml b/.github/workflows/phplint.yml
index c79bf34d..53d6c61e 100644
--- a/.github/workflows/phplint.yml
+++ b/.github/workflows/phplint.yml
@@ -39,8 +39,8 @@ jobs:
       - name: Install Composer dependencies
         uses: "ramsey/composer-install@v2"
         with:
-          # Bust the cache at least once a month - output format: YYYY-MM-DD.
-          custom-cache-suffix: $(date -u -d "-0 month -$(($(date +%d)-1)) days" "+%F")
+          # Bust the cache at least once a month - output format: YYYY-MM.
+          custom-cache-suffix: $(date -u "+%Y-%m")
 
       - name: Lint against parse errors
         run: composer lint -- --checkstyle | cs2pr
diff --git a/.github/workflows/quicktest.yml b/.github/workflows/quicktest.yml
index 5427a48f..24205abd 100644
--- a/.github/workflows/quicktest.yml
+++ b/.github/workflows/quicktest.yml
@@ -60,8 +60,8 @@ jobs:
         uses: "ramsey/composer-install@v2"
         with:
           composer-options: '--optimize-autoloader'
-          # Bust the cache at least once a month - output format: YYYY-MM-DD.
-          custom-cache-suffix: $(date -u -d "-0 month -$(($(date +%d)-1)) days" "+%F")
+          # Bust the cache at least once a month - output format: YYYY-MM.
+          custom-cache-suffix: $(date -u "+%Y-%m")
 
       - name: Run integration tests
         run: vendor/bin/phpunit --no-coverage
diff --git a/.github/workflows/securitycheck.yml b/.github/workflows/securitycheck.yml
index 36636d96..4c4e445b 100644
--- a/.github/workflows/securitycheck.yml
+++ b/.github/workflows/securitycheck.yml
@@ -37,8 +37,8 @@ jobs:
       - name: Install Composer dependencies
         uses: "ramsey/composer-install@v2"
         with:
-          # Bust the cache at least once a month - output format: YYYY-MM-DD.
-          custom-cache-suffix: $(date -u -d "-0 month -$(($(date +%d)-1)) days" "+%F")
+          # Bust the cache at least once a month - output format: YYYY-MM.
+          custom-cache-suffix: $(date -u "+%Y-%m")
 
       - name: Download security checker
         # yamllint disable-line rule:line-length