diff --git a/repos/system_upgrade/common/actors/initramfs/upgradeinitramfsgenerator/libraries/upgradeinitramfsgenerator.py b/repos/system_upgrade/common/actors/initramfs/upgradeinitramfsgenerator/libraries/upgradeinitramfsgenerator.py
index b26cf87058..b33b20e390 100644
--- a/repos/system_upgrade/common/actors/initramfs/upgradeinitramfsgenerator/libraries/upgradeinitramfsgenerator.py
+++ b/repos/system_upgrade/common/actors/initramfs/upgradeinitramfsgenerator/libraries/upgradeinitramfsgenerator.py
@@ -212,7 +212,8 @@ def copy_boot_files(context):
             if len(hmac_file_lines) > 1:
                 details = ('Expected the target kernel HMAC file to containing only one HMAC line, '
                            'found {0}'.format(len(hmac_file_lines)))
-                raise StopActorExecutionError('Failed to prepare HMAC file for upgrade kernel.', details={'details': details})
+                raise StopActorExecutionError('Failed to prepare HMAC file for upgrade kernel.',
+                                              details={'details': details})
 
             # Keep only non-empty strings after splitting on space
             hmac, dummy_target_kernel_name = [fragment for fragment in hmac_file_lines[0].split(' ') if fragment]