diff --git a/.github/workflows/scala.yml b/.github/workflows/scala.yml
index 2483ca3..7b81902 100644
--- a/.github/workflows/scala.yml
+++ b/.github/workflows/scala.yml
@@ -21,5 +21,7 @@ jobs:
       with:
         java-version: '11'
         distribution: 'temurin'
+    - name: build simulator
+      run: make init
     - name: Run tests
       run: sbt test
diff --git a/Makefile b/Makefile
index e7ab82e..552e119 100644
--- a/Makefile
+++ b/Makefile
@@ -4,6 +4,11 @@
 # including cosimulation and check against Morten's simulator
 # TODO: cleanup
 
+# init submodules and build leros-sim
+init:
+	git submodule update --init --recursive
+	cd leros-sim && ./build.sh
+
 # runs all tests
 test:
 	sbt test
diff --git a/src/test/scala/leros/CompareTest.scala b/src/test/scala/leros/CompareTest.scala
index dd155f3..7acf37c 100644
--- a/src/test/scala/leros/CompareTest.scala
+++ b/src/test/scala/leros/CompareTest.scala
@@ -17,7 +17,7 @@ import scala.collection.mutable.ListBuffer
 
 class CompareTest extends AnyFlatSpec with ChiselScalatestTester {
 
-  val simulator = "../leros-sim/build-leros-sim/leros-sim"
+  val simulator = "leros-sim/build-leros-sim/leros-sim"
   if ((new java.io.File(simulator)).isFile) {
 
     val progs = leros.shared.Util.getProgs()