diff --git a/src/core/unit.h b/src/core/unit.h
index e0e76e520..3c9a64f89 100644
--- a/src/core/unit.h
+++ b/src/core/unit.h
@@ -239,7 +239,7 @@ struct Unit {
         bool cgroup_subtree_mask_valid:1;
 
         /* Did we already invoke unit_coldplug() for this unit? */
-        bool coldplugged;
+        bool coldplugged:1;
 };
 
 struct UnitStatusMessageFormats {