diff --git a/testing/mochitest/mach_commands.py b/testing/mochitest/mach_commands.py
index 5e08f7c3b420..f5ecb6f25a07 100644
--- a/testing/mochitest/mach_commands.py
+++ b/testing/mochitest/mach_commands.py
@@ -177,7 +177,7 @@ class MochitestRunner(MozbuildObject):
             options.manifestFile = manifest
 
         # Firefox for Android doesn't use e10s
-        if options.app is None or 'geckoview' not in options.app:
+        if options.app is not None and 'geckoview' not in options.app:
             options.e10s = False
             print("using e10s=False for non-geckoview app")