diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index bbe82bae54cee..3c5355e7abdcd 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -272,11 +272,12 @@ jobs:
       - run: >
           podman run --init --privileged --rm -it -v $(pwd):$(pwd) -w $(pwd)
           docker.io/pbolinaro/qemu-ci:debian-all-test-cross
-          bash -cx "env ASAN_OPTIONS=detect_leaks=0 make -k check-tcg"
+          bash -cx "env ASAN_OPTIONS=detect_leaks=0 make -k -j $(nproc) check-tcg"
 
-  # run all meson tests, including functional. Run -j1 to avoid sporadic issues.
+  # run all meson tests, including functional.
   # block tests are not ran because they don't support sanitizers:
   # https://gitlab.com/qemu-project/qemu/-/blob/master/tests/qemu-iotests/meson.build
+  # Limit parallelism because it creates timeout.
   check:
     needs: checkapply
     runs-on: ubuntu-24.04
@@ -291,7 +292,7 @@ jobs:
       - run: >
           podman run --init --privileged --rm -it -v /dev/kvm:/dev/kvm -v $(pwd):$(pwd) -w $(pwd)
           docker.io/pbolinaro/qemu-ci:debian-precache-tests
-          bash -cx "env ASAN_OPTIONS=detect_leaks=0 make -k check SPEED=thorough TIMEOUT_MULTIPLIER=5 V=1"
+          bash -cx "env ASAN_OPTIONS=detect_leaks=0 make -k -j $(($(nproc) / 2)) check SPEED=thorough TIMEOUT_MULTIPLIER=5 V=1"
 
   # iotests do not support sanitizers, so we run them in their own job
   check-block:
@@ -308,7 +309,7 @@ jobs:
       - run: >
           podman run --init --privileged --rm -it -v /dev/kvm:/dev/kvm -v $(pwd):$(pwd) -w $(pwd)
           docker.io/pbolinaro/qemu-ci:debian-precache-tests
-          bash -cx "./build/pyvenv/bin/meson test -C build --suite block --suite block-slow --suite block-thorough -j 1 --timeout-multiplier 5 --verbose"
+          bash -cx "./build/pyvenv/bin/meson test -C build --suite block --suite block-slow --suite block-thorough -j $(nproc) --timeout-multiplier 5 --verbose"
 
   check-avocado:
     needs: checkapply
@@ -326,4 +327,4 @@ jobs:
       - run: >
           podman run --init --privileged --rm -it -v /dev/kvm:/dev/kvm -v $(pwd):$(pwd) -w $(pwd)
           docker.io/pbolinaro/qemu-ci:debian-precache-tests
-          bash -cx "env ASAN_OPTIONS=detect_leaks=0 make -k check-avocado V=1"
+          bash -cx "env ASAN_OPTIONS=detect_leaks=0 make -k -j $(nproc) check-avocado V=1"