diff --git a/.gitlab-ci.d/crossbuilds.yml b/.gitlab-ci.d/crossbuilds.yml
index 459273f..1e21d08 100644
--- a/.gitlab-ci.d/crossbuilds.yml
+++ b/.gitlab-ci.d/crossbuilds.yml
@@ -62,7 +62,11 @@
     IMAGE: debian-i686-cross
     ACCEL: tcg-interpreter
     EXTRA_CONFIGURE_OPTS: --target-list=i386-softmmu,i386-linux-user,aarch64-softmmu,aarch64-linux-user,ppc-softmmu,ppc-linux-user --disable-plugins --disable-kvm
-    MAKE_CHECK_ARGS: check check-tcg
+    # Force tests to run in series, to see whether this
+    # reduces the flakiness of this CI job. The CI
+    # environment by default shows us 8 CPUs and so we
+    # would otherwise be using a parallelism of 9.
+    MAKE_CHECK_ARGS: check check-tcg -j1
 
 cross-mipsel-system:
   extends: .cross_system_build_job