diff --git a/pyproject.toml b/pyproject.toml
index a50961f98..01bb31783 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -92,6 +92,8 @@ xfail_strict = true
 [tool.coverage.run]
 branch = true
 source = ["src/taskgraph/", "src/taskgraph/run-task/", "packages", "test"]
+parallel = true
+patch = ["_exit"]
 
 ### Lint and Format
 [tool.ruff]
diff --git a/taskcluster/kinds/test/linux.yml b/taskcluster/kinds/test/linux.yml
index 94f73ba58..1e363a468 100644
--- a/taskcluster/kinds/test/linux.yml
+++ b/taskcluster/kinds/test/linux.yml
@@ -48,7 +48,8 @@ unit:
         symbol: unit(py{matrix[python]})
     run:
         command: >-
-            uv run coverage run --data-file /builds/worker/artifacts/coverage --context=py{matrix[python]} -m pytest -vv
+            uv run coverage run --data-file /builds/worker/artifacts/coverage --context=py{matrix[python]} -m pytest -vv &&
+            uv run coverage combine --data-file /builds/worker/artifacts/coverage
 
 unit-multithread:
     description: "Run unit tests with py{matrix[python]} on Linux with multithreading enabled"
@@ -68,7 +69,8 @@ unit-multithread:
         symbol: unit-multithread(py{matrix[python]})
     run:
         command: >-
-            uv run coverage run --data-file /builds/worker/artifacts/coverage --context=py{matrix[python]} -m pytest -vv
+            uv run coverage run --data-file /builds/worker/artifacts/coverage --context=py{matrix[python]} -m pytest -vv &&
+            uv run coverage combine --data-file /builds/worker/artifacts/coverage
 
 unit-serial:
     description: "Run unit tests with py{matrix[python]} on Linux in serial mode"
@@ -88,7 +90,8 @@ unit-serial:
         symbol: unit-serial(py{matrix[python]})
     run:
         command: >-
-            uv run coverage run --data-file /builds/worker/artifacts/coverage --context=py{matrix[python]} -m pytest -vv
+            uv run coverage run --data-file /builds/worker/artifacts/coverage --context=py{matrix[python]} -m pytest -vv &&
+            uv run coverage combine --data-file /builds/worker/artifacts/coverage
 
 integration:
     description: "Run unit tests with py{matrix[python]} on Linux with resolution {matrix[resolution]}"