--- a/testing/taskcluster/tasks/tests/fx_linux64_mochitest_plain.yml
+++ b/testing/taskcluster/tasks/tests/fx_linux64_mochitest_plain.yml
@@ -10,16 +10,16 @@ task:
     description: Mochitest plain run {{chunk}}
   payload:
     capabilities:
       devices:
         loopbackVideo: true
         loopbackAudio: true
   extra:
     chunks:
-      total: 5
+      total: 8
     suite:
       name: mochitest
       flavor: plain-chunked
     treeherder:
       groupName: Desktop mochitests
       groupSymbol: tc-M
       symbol: {{chunk}}