diff --git a/.github/workflows/mediawiki-tests.yml b/.github/workflows/mediawiki-tests.yml
index e74c122..5657499 100644
--- a/.github/workflows/mediawiki-tests.yml
+++ b/.github/workflows/mediawiki-tests.yml
@@ -22,6 +22,16 @@ jobs:
             php: 7.4
             continue-on-error: false
 
+          # Latest MediaWiki release branch - PHP 7.3
+          - mw: 'REL1_37'
+            php: 7.3
+            continue-on-error: true
+
+          # Latest MediaWiki release branch - PHP 7.4
+          - mw: 'REL1_37'
+            php: 7.4
+            continue-on-error: true
+
           # Latest MediaWiki master - PHP 7.3
           - mw: 'master'
             php: 7.3
diff --git a/.github/workflows/phpunit-tests.yml b/.github/workflows/phpunit-tests.yml
index 1456536..bd14d35 100644
--- a/.github/workflows/phpunit-tests.yml
+++ b/.github/workflows/phpunit-tests.yml
@@ -24,6 +24,18 @@ jobs:
             mysql: '5.7'
             continue-on-error: false
 
+          # Latest MediaWiki release branch - PHP 7.3
+          - mw: 'REL1_37'
+            php: 7.3
+            mysql: '5.7'
+            continue-on-error: false
+
+          # Latest MediaWiki release branch - PHP 7.4
+          - mw: 'REL1_37'
+            php: 7.4
+            mysql: '5.7'
+            continue-on-error: false
+
           # Latest MW master - PHP 7.3
           - mw: 'master'
             php: 7.3
@@ -102,9 +114,10 @@ jobs:
       - name: Run PHPUnit
         continue-on-error: ${{ matrix.continue-on-error }}
         run: |
-          [[ '${{ matrix.mw }}' != 'master' ]] && PHPUNIT_ARGS='--use-normal-tables' ||  PHPUNIT_ARGS=''
+          [[ '${{ matrix.mw }}' != 'master' && '${{ matrix.mw }}' != 'REL1_37' ]] && PHPUNIT_ARGS='--use-normal-tables' ||  PHPUNIT_ARGS=''
           php tests/phpunit/phpunit.php $PHPUNIT_ARGS extensions/PortableInfobox/tests/phpunit
 #         php tests/phpunit/phpunit.php tests/phpunit/includes/Storage/PageUpdaterTest.php
 
+        # In MediaWiki 1.37.0+ this is now an environmental variable
         env:
           PHPUNIT_USE_NORMAL_TABLES: 1