diff --git a/migrations/versions/4ab08bf12666_.py b/migrations/versions/4ab08bf12666_.py
index d0af4066..fcc57315 100644
--- a/migrations/versions/4ab08bf12666_.py
+++ b/migrations/versions/4ab08bf12666_.py
@@ -35,18 +35,18 @@ def upgrade():
 
     op.drop_index('ix_message_correlation_property_identifier', table_name='message_correlation_property')
     op.drop_index('message_correlation_property_unique', table_name='message_correlation_property')
-    op.drop_constraint(u'message_correlation_ibfk_1', 'message_correlation', type_='foreignkey')
+    op.drop_constraint('message_correlation_ibfk_1', 'message_correlation', type_='foreignkey')
     op.drop_table('message_correlation_property')
     op.drop_index('ix_message_correlation_message_correlation_property_id', table_name='message_correlation')
     op.drop_index('ix_message_correlation_name', table_name='message_correlation')
     op.drop_index('ix_message_correlation_process_instance_id', table_name='message_correlation')
     op.drop_index('ix_message_correlation_value', table_name='message_correlation')
-    op.drop_constraint(u'message_correlation_message_instance_ibfk_1', 'message_correlation_message_instance', type_='foreignkey')
-    op.drop_constraint(u'message_triggerable_process_model_ibfk_1', 'message_triggerable_process_model', type_='foreignkey')
+    op.drop_constraint('message_correlation_message_instance_ibfk_1', 'message_correlation_message_instance', type_='foreignkey')
+    op.drop_constraint('message_triggerable_process_model_ibfk_1', 'message_triggerable_process_model', type_='foreignkey')
     op.drop_table('message_correlation')
     op.drop_index('ix_message_model_identifier', table_name='message_model')
     op.drop_index('ix_message_model_name', table_name='message_model')
-    op.drop_constraint(u'message_instance_ibfk_1', 'message_instance', type_='foreignkey')
+    op.drop_constraint('message_instance_ibfk_1', 'message_instance', type_='foreignkey')
     op.drop_table('message_model')
     op.drop_table('message_correlation_message_instance')
     op.add_column('message_instance', sa.Column('name', sa.String(length=255), nullable=True))