diff --git a/guix-data-service/database.scm b/guix-data-service/database.scm
index 3a39798..25305b2 100644
--- a/guix-data-service/database.scm
+++ b/guix-data-service/database.scm
@@ -153,8 +153,7 @@
       (pg-conn-finish conn)
       (hash-remove! (%postgresql-connections-hash-table)
                     (current-thread))
-      (fluid-set! %thread-postgresql-connection
-                  conn))))
+      (fluid-set! %thread-postgresql-connection #f))))
 
 (define* (with-postgresql-transaction conn f
                                       #:key always-rollback?)