diff --git a/build.sbt b/build.sbt
index add7a0b..fb50b85 100644
--- a/build.sbt
+++ b/build.sbt
@@ -89,3 +89,9 @@ printTests := {
     println(t.name)
   }
 }
+
+
+// run in parallel with forking
+fork := true
+Test / testForkedParallel := true
+Test / parallelExecution := true
\ No newline at end of file
diff --git a/src/test/scala/gcd/GcdTesters2.scala b/src/test/scala/gcd/GcdTesters2.scala
index 4a07b0d..f4ed25e 100644
--- a/src/test/scala/gcd/GcdTesters2.scala
+++ b/src/test/scala/gcd/GcdTesters2.scala
@@ -51,3 +51,22 @@ class GcdTesters2 extends FreeSpec with ChiselScalatestTester {
     }
   }
 }
+
+class GcdTesters3 extends GcdTesters2 {
+}
+class GcdTesters4 extends GcdTesters2 {
+}
+class GcdTesters5 extends GcdTesters2 {
+}
+class GcdTesters6 extends GcdTesters2 {
+}
+class GcdTesters7 extends GcdTesters2 {
+}
+class GcdTesters8 extends GcdTesters2 {
+}
+class GcdTesters9 extends GcdTesters2 {
+}
+class GcdTesters10 extends GcdTesters2 {
+}
+class GcdTesters11 extends GcdTesters2 {
+}