diff --git a/src/org/nutz/mvc/adaptor/injector/JsonInjector.java b/src/org/nutz/mvc/adaptor/injector/JsonInjector.java
index 3e51cc6179..a9204a978e 100644
--- a/src/org/nutz/mvc/adaptor/injector/JsonInjector.java
+++ b/src/org/nutz/mvc/adaptor/injector/JsonInjector.java
@@ -2,6 +2,7 @@
 
 import java.lang.reflect.Type;
 import java.util.Map;
+import java.util.Objects;
 
 import javax.servlet.ServletContext;
 import javax.servlet.http.HttpServletRequest;
@@ -33,7 +34,7 @@ public Object get(    ServletContext sc,
         if (null == name)
             return Mapl.maplistToObj(refer, type);
 
-        Map<String, Object> map = (Map<String, Object>)refer;
+        Map<String, Object> map = (Map<String, Object>) Objects.requireNonNull(refer, "refer");
         Object theObj = map.get(name);
         if (null == theObj)
             return null;
diff --git a/test/org/nutz/mvc/adaptor/injector/JsonInjectorTest.java b/test/org/nutz/mvc/adaptor/injector/JsonInjectorTest.java
new file mode 100644
index 0000000000..e455919d68
--- /dev/null
+++ b/test/org/nutz/mvc/adaptor/injector/JsonInjectorTest.java
@@ -0,0 +1,24 @@
+package org.nutz.mvc.adaptor.injector;
+
+import static org.junit.Assert.*;
+
+import org.junit.Test;
+
+/**
+ * @author Heewon Lee (pingpingy03@gmail.com)
+ */
+public class JsonInjectorTest {
+
+    @Test
+    public void test_null_refer() {
+        // 准备数据
+        JsonInjector inj = new JsonInjector(null, "");
+
+        // 检测
+        Throwable exc = assertThrows(NullPointerException.class, () -> {
+            inj.get(null, null, null, null);
+        });
+        assertEquals("refer", exc.getMessage());
+    }
+
+}