diff --git a/Makefile b/Makefile
index e017e60..ca9faab 100644
--- a/Makefile
+++ b/Makefile
@@ -30,7 +30,11 @@ ISOLATIONCHECKS = corner_cases
 
 check: isolationcheck
 
-installcheck: isolationcheck
+installcheck: submake-isolation
+	$(MKDIR_P) isolation_output
+	$(pg_isolation_regress_installcheck) \
+	  --outputdir=isolation_output \
+	$(ISOLATIONCHECKS)
 
 isolationcheck: | submake-isolation temp-install
 	$(MKDIR_P) isolation_output
diff --git a/pg_query_state.c b/pg_query_state.c
index a4a7d1b..935fbf8 100644
--- a/pg_query_state.c
+++ b/pg_query_state.c
@@ -541,14 +541,18 @@ pg_query_state(PG_FUNCTION_ARGS)
 				break;
 			}
 		}
-		pg_atomic_write_u32(&counterpart_userid->n_peers, 1);
-		params->reqid = ++reqid;
-		pg_write_barrier();
 
 		counterpart_user_id = GetRemoteBackendUserId(proc);
 		if (!(superuser() || GetUserId() == counterpart_user_id))
+		{
+			UnlockShmem(&tag);
 			ereport(ERROR, (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
 							errmsg("permission denied")));
+		}
+
+		pg_atomic_write_u32(&counterpart_userid->n_peers, 1);
+		params->reqid = ++reqid;
+		pg_write_barrier();
 
 		bg_worker_procs = GetRemoteBackendWorkers(proc);