diff --git a/.github/workflows/maven.yml b/.github/workflows/maven.yml
index 556452ee..59d2d8f1 100644
--- a/.github/workflows/maven.yml
+++ b/.github/workflows/maven.yml
@@ -20,5 +20,9 @@ jobs:
                 uses: actions/setup-java@v1
                 with:
                     java-version: 1.8
+            -   name: Checkout submodules
+                uses: srt32/git-actions@v0.0.3
+                with:
+                  args: git submodule update --init --recursive
             -   name: Build with Maven
                 run: mvn -B package --file pom.xml