diff --git a/stat.c b/stat.c
index 77e389c..03dc458 100644
--- a/stat.c
+++ b/stat.c
@@ -1077,6 +1077,10 @@
 		dst->agg[i] += src->agg[i];
 	}
 
+	if (!dst->kb_base)
+		dst->kb_base = src->kb_base;
+	if (!dst->unit_base)
+		dst->unit_base = src->unit_base;
 }
 
 void sum_thread_stats(struct thread_stat *dst, struct thread_stat *src, int nr)