diff --git a/core/src/main/java/cn/edu/tsinghua/iginx/engine/shared/operator/type/OperatorType.java b/core/src/main/java/cn/edu/tsinghua/iginx/engine/shared/operator/type/OperatorType.java
index 7555478f0..0ff8359a0 100644
--- a/core/src/main/java/cn/edu/tsinghua/iginx/engine/shared/operator/type/OperatorType.java
+++ b/core/src/main/java/cn/edu/tsinghua/iginx/engine/shared/operator/type/OperatorType.java
@@ -80,7 +80,7 @@ private static class OperatorTypeCounter
     }
 
     public static boolean isBinaryOperator(OperatorType op) {
-        return 40 < op.value && op.value < 49;
+        return op.value >= 40 && op.value <= 49;
     }
 
     public static boolean isUnaryOperator(OperatorType op) {