diff --git a/core/src/main/java/cn/edu/tsinghua/iot/benchmark/client/SchemaClient.java b/core/src/main/java/cn/edu/tsinghua/iot/benchmark/client/SchemaClient.java
index e86b04dc7..409ee466e 100644
--- a/core/src/main/java/cn/edu/tsinghua/iot/benchmark/client/SchemaClient.java
+++ b/core/src/main/java/cn/edu/tsinghua/iot/benchmark/client/SchemaClient.java
@@ -89,7 +89,7 @@ public Boolean call() {
 
         // register
         try {
-          // When the return value is non-empty, the registerSchema is successful.
+          // When the return value is not null, the registerSchema is successful.
           result = (null != dbWrapper.registerSchema(deviceSchemas));
         } catch (TsdbException e) {
           LOGGER.error("Register {} schema failed because ", config.getNET_DEVICE(), e);