diff --git a/.github/workflows/test-and-release.yml b/.github/workflows/test-and-release.yml
index 891eb89..583d7ee 100644
--- a/.github/workflows/test-and-release.yml
+++ b/.github/workflows/test-and-release.yml
@@ -15,7 +15,7 @@ jobs:
       - uses: actions/setup-java@v4
         with:
           distribution: 'temurin'
-          java-version: '11'
+          java-version: '21'
       - name: Setup Clojure
         uses: DeLaGuardo/setup-clojure@master
         with:
diff --git a/.github/workflows/test-and-snapshot.yml b/.github/workflows/test-and-snapshot.yml
index 3d9eb91..11606c8 100644
--- a/.github/workflows/test-and-snapshot.yml
+++ b/.github/workflows/test-and-snapshot.yml
@@ -13,7 +13,7 @@ jobs:
       - uses: actions/setup-java@v4
         with:
           distribution: 'temurin'
-          java-version: '11'
+          java-version: '21'
       - name: Setup Clojure
         uses: DeLaGuardo/setup-clojure@master
         with:
@@ -75,4 +75,4 @@ jobs:
             ~/.cpcache
           key: ${{ runner.os }}-${{ hashFiles('**/deps.edn') }}
       - name: Run Tests
-        run: clojure -T:build test
+        run: clojure -T:build:jdk${{ matrix.java }} test
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index cd9b86f..9a664d8 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -38,7 +38,7 @@ jobs:
           NEXT_JDBC_TEST_MYSQL: yes
           NEXT_JDBC_TEST_MARIADB: yes
       - name: Run All Tests
-        run: clojure -M:test:runner
+        run: clojure -M:test:runner:jdk${{ matrix.java }}
         env:
           MYSQL_ROOT_PASSWORD: testing
           NEXT_JDBC_TEST_MYSQL: yes
diff --git a/deps.edn b/deps.edn
index 30ccdb4..c71aaae 100644
--- a/deps.edn
+++ b/deps.edn
@@ -40,8 +40,6 @@
                       io.zonky.test.postgres/embedded-postgres-binaries-windows-amd64 {:mvn/version "17.4.0"}
                       org.xerial/sqlite-jdbc {:mvn/version "3.49.1.0"}
                       com.microsoft.sqlserver/mssql-jdbc {:mvn/version "12.10.0.jre11"}
-                      ;; only need the XTDB JDBC module:
-                      com.xtdb/xtdb-jdbc {:mvn/version "2.0.0-beta7"}
                       ;; use log4j2 to reduce log noise during testing:
                       org.apache.logging.log4j/log4j-api {:mvn/version "2.24.3"}
                       ;; bridge everything into log4j:
@@ -52,5 +50,9 @@
                       org.apache.logging.log4j/log4j-slf4j2-impl {:mvn/version "2.24.3"}}
          :jvm-opts ["-Dlog4j2.configurationFile=log4j2-info.properties"]}
   :runner {:main-opts ["-m" "lazytest.main"]}
+  :jdk11 {}
+  :jdk17 {}
+  :jdk21 {:extra-deps {;; only need the XTDB JDBC module:
+                       com.xtdb/xtdb-jdbc {:mvn/version "2.0.0-beta7"}}}
   :jdk24 {:jvm-opts [;; for SQLite on JDK 24 locally
                      "--enable-native-access=ALL-UNNAMED"]}}}
diff --git a/run-tests.clj b/run-tests.clj
index f86bd9f..60eb926 100755
--- a/run-tests.clj
+++ b/run-tests.clj
@@ -10,6 +10,9 @@
                  (str "-M"
                       (when v (str ":" v))
                       ":test:runner"
+                      ;; jdk21+ adds xtdb:
+                      (when (System/getenv "NEXT_JDBC_TEST_XTDB")
+                        ":jdk21")
                       ;; to suppress native access warnings on JDK24:
                       ":jdk24")
                  "--output" "dots")]
diff --git a/test/next/jdbc/test_fixtures.clj b/test/next/jdbc/test_fixtures.clj
index 0cab24a..65aa5da 100644
--- a/test/next/jdbc/test_fixtures.clj
+++ b/test/next/jdbc/test_fixtures.clj
@@ -67,7 +67,10 @@
 (def ^:private test-xtdb-map {:dbtype "xtdb" :dbname "xtdb"})
 
 (def ^:private test-xtdb
-  (when (System/getenv "NEXT_JDBC_TEST_XTDB") test-xtdb-map))
+  (when (and (System/getenv "NEXT_JDBC_TEST_XTDB")
+             ;; only if we're on jdk21+
+             (str/starts-with? (System/getProperty "java.version") "2"))
+    test-xtdb-map))
 
 (def ^:private test-db-specs
   (cond-> [test-derby test-h2-mem test-h2 test-hsql test-sqlite]