diff --git a/python/mozbuild/mozbuild/mach_commands.py b/python/mozbuild/mozbuild/mach_commands.py
--- a/python/mozbuild/mozbuild/mach_commands.py
+++ b/python/mozbuild/mozbuild/mach_commands.py
@@ -1418,11 +1418,11 @@
                     record.algorithm, unpack=record.unpack,
                     version=record.version, visibility=record.visibility,
                     setup=record.setup)
 
         if from_build:
-            if 'TASK_ID' in os.environ:
+            if 'MOZ_AUTOMATION' in os.environ:
                 self.log(logging.ERROR, 'artifact', {},
                          'Do not use --from-build in automation; all dependencies '
                          'should be determined in the decision task.')
                 return 1
             from taskgraph.optimize import IndexSearch