diff --git a/src/main/java/org/ssssssss/script/runtime/handle/FunctionCallHandle.java b/src/main/java/org/ssssssss/script/runtime/handle/FunctionCallHandle.java
index 6b186b53ac733841ef74cdf809a5342a054555a5..fb2fd44724074b7de0bd5938b377b07129208043 100644
--- a/src/main/java/org/ssssssss/script/runtime/handle/FunctionCallHandle.java
+++ b/src/main/java/org/ssssssss/script/runtime/handle/FunctionCallHandle.java
@@ -171,7 +171,7 @@ public class FunctionCallHandle {
 			if (optional) {
 				return null;
 			}
-			throw new NullPointerException("target is null");
+			throw new NullPointerException(String.format("Cannot read properties of null (reading '%s')", name));
 		}
 		if ("class".equals(name)) {
 			return target instanceof Class ? target : target.getClass();
@@ -310,7 +310,7 @@ public class FunctionCallHandle {
 
 	public static Object set_variable_value(RuntimeContext runtimeContext, Object target, Object name, Object value) throws Throwable {
 		if (target == null) {
-			throw new NullPointerException("target is null");
+			throw new NullPointerException(String.format("Cannot read properties of null (reading '%s')", name));
 		}
 		if (name == null) {
 			throw new NullPointerException("key is null");