diff --git a/x-pack/qa/third-party/active-directory/build.gradle b/x-pack/qa/third-party/active-directory/build.gradle
index 5156d20dd1d12..1f9b17217e47d 100644
--- a/x-pack/qa/third-party/active-directory/build.gradle
+++ b/x-pack/qa/third-party/active-directory/build.gradle
@@ -29,4 +29,7 @@ tasks.named("test").configure {
   systemProperty 'tests.security.manager', 'false'
   include '**/*IT.class'
   include '**/*Tests.class'
+
+  // Limit how many concurrent docker test fixtures we are running
+  maxParallelForks = 1
 }