diff --git a/src/core/manager.h b/src/core/manager.h
index ff73fb3e85..6fff7b2437 100644
--- a/src/core/manager.h
+++ b/src/core/manager.h
@@ -244,7 +244,7 @@ struct Manager {
          * file system */
         int pin_cgroupfs_fd;
 
-        int gc_marker;
+        unsigned gc_marker;
 
         /* Flags */
         ManagerExitCode exit_code:5;