diff --git a/.gitlab-ci/vkd3d-runner.sh b/.gitlab-ci/vkd3d-runner.sh
index 0f95f1b3c66..bea8cf84ebb 100755
--- a/.gitlab-ci/vkd3d-runner.sh
+++ b/.gitlab-ci/vkd3d-runner.sh
@@ -92,7 +92,7 @@ printf "%s\n" "Running vkd3d-proton testsuite..."
 
 LOGFILE="$RESULTS/vkd3d-proton-log.txt"
 TEST_LOGS="$PWD/test-logs"
-(cd /vkd3d-proton-tests && tests/test-runner.sh x64/bin/d3d12 --output-dir "$TEST_LOGS" | tee "$LOGFILE")
+(cd /vkd3d-proton-tests && tests/test-runner.sh x64/bin/d3d12 --jobs "${FDO_CI_CONCURRENT:-4}" --output-dir "$TEST_LOGS" | tee "$LOGFILE")
 
 printf '\n\n'
 
diff --git a/src/amd/ci/gitlab-ci.yml b/src/amd/ci/gitlab-ci.yml
index 0f93910da4e..b489103000d 100644
--- a/src/amd/ci/gitlab-ci.yml
+++ b/src/amd/ci/gitlab-ci.yml
@@ -331,6 +331,8 @@ vkd3d-tahiti-valve:
     - .radv-valve-manual-rules
   variables:
     GPU_VERSION: radv-tahiti
+    # Random tests fail/crash when trying to run them in parallel
+    FDO_CI_CONCURRENT: 1
 
 vkd3d-polaris10-valve:
   extends:
@@ -340,6 +342,8 @@ vkd3d-polaris10-valve:
     - .radv-valve-manual-rules
   variables:
     GPU_VERSION: radv-polaris10
+    # Random tests fail/crash when trying to run them in parallel
+    FDO_CI_CONCURRENT: 1
 
 vkd3d-vega10-valve:
   extends:
@@ -349,6 +353,8 @@ vkd3d-vega10-valve:
     - .radv-valve-manual-rules
   variables:
     GPU_VERSION: radv-vega10
+    # Random tests fail/crash when trying to run them in parallel
+    FDO_CI_CONCURRENT: 1
 
 vkd3d-renoir-valve:
   extends:
@@ -358,6 +364,8 @@ vkd3d-renoir-valve:
     - .radv-valve-manual-rules
   variables:
     GPU_VERSION: radv-renoir
+    # Random tests fail/crash when trying to run them in parallel
+    FDO_CI_CONCURRENT: 1
 
 vkd3d-navi10-valve:
   extends:
@@ -367,6 +375,8 @@ vkd3d-navi10-valve:
     - .radv-valve-manual-rules
   variables:
     GPU_VERSION: radv-navi10
+    # Random tests fail/crash when trying to run them in parallel
+    FDO_CI_CONCURRENT: 1
 
 vkd3d-navi21-valve:
   extends:
@@ -376,6 +386,8 @@ vkd3d-navi21-valve:
     - .radv-valve-manual-rules
   variables:
     GPU_VERSION: radv-navi21
+    # Random tests fail/crash when trying to run them in parallel
+    FDO_CI_CONCURRENT: 1
 
 vkd3d-vangogh-valve:
   extends:
@@ -385,6 +397,8 @@ vkd3d-vangogh-valve:
     - .radv-valve-manual-rules
   variables:
     GPU_VERSION: radv-vangogh
+    # Random tests fail/crash when trying to run them in parallel
+    FDO_CI_CONCURRENT: 1
 
 vkd3d-navi31-valve:
   extends:
@@ -394,3 +408,5 @@ vkd3d-navi31-valve:
     - .radv-valve-manual-rules
   variables:
     GPU_VERSION: radv-navi31
+    # Random tests fail/crash when trying to run them in parallel
+    FDO_CI_CONCURRENT: 1
diff --git a/src/nouveau/ci/gitlab-ci.yml b/src/nouveau/ci/gitlab-ci.yml
index 4b4b519723a..72c951d4951 100644
--- a/src/nouveau/ci/gitlab-ci.yml
+++ b/src/nouveau/ci/gitlab-ci.yml
@@ -23,3 +23,5 @@ nvk-ga106-vkd3d-valve:
     HWCI_TEST_SCRIPT: install/vkd3d-runner.sh
     B2C_TIMEOUT_BOOT_MINUTES: 10
     B2C_TIMEOUT_OVERALL_MINUTES: 12
+    # Random tests fail/crash when trying to run them in parallel
+    FDO_CI_CONCURRENT: 1