diff --git a/testable-agent/src/main/java/com/alibaba/testable/agent/handler/TestClassHandler.java b/testable-agent/src/main/java/com/alibaba/testable/agent/handler/TestClassHandler.java
index e35fe22..181e190 100644
--- a/testable-agent/src/main/java/com/alibaba/testable/agent/handler/TestClassHandler.java
+++ b/testable-agent/src/main/java/com/alibaba/testable/agent/handler/TestClassHandler.java
@@ -56,17 +56,28 @@ public class TestClassHandler extends BaseClassHandler {
         mn.access |= ACC_PUBLIC;
         if ((mn.access & ACC_STATIC) == 0) {
             mn.access |= ACC_STATIC;
-            // remote `this` reference
-            mn.localVariables.remove(0);
+            // remove `this` reference
+            LocalVariableNode thisRef = null;
             for (LocalVariableNode vn : mn.localVariables) {
-                vn.index--;
+                if (vn.index == 0) {
+                    thisRef = vn;
+                } else {
+                    vn.index--;
+                }
+            }
+            if (thisRef != null) {
+                mn.localVariables.remove(thisRef);
+            } else {
+                LogUtil.error("Fail to find `this` reference in none-static method " + getName(cn, mn));
+                return;
             }
             for (AbstractInsnNode in : mn.instructions) {
                 if (in.getOpcode() >= ILOAD && in.getOpcode() <= SASTORE && in instanceof VarInsnNode) {
                     if (((VarInsnNode)in).var > 0) {
                         ((VarInsnNode)in).var--;
                     } else if (in.getOpcode() == ALOAD) {
-                        LogUtil.warn("Attempt to access none-static member in mock method !");
+                        LogUtil.error("Attempt to access none-static member in mock method " + getName(cn, mn));
+                        return;
                     }
                 }
             }
@@ -74,6 +85,10 @@ public class TestClassHandler extends BaseClassHandler {
         }
     }
 
+    private String getName(ClassNode cn, MethodNode mn) {
+        return cn.name + ":" + mn.name;
+    }
+
     private boolean isMockMethod(MethodNode mn) {
         if (mn.visibleAnnotations == null) {
             return false;
diff --git a/testable-core/src/main/java/com/alibaba/testable/core/util/LogUtil.java b/testable-core/src/main/java/com/alibaba/testable/core/util/LogUtil.java
index 2e82b94..3c547e4 100644
--- a/testable-core/src/main/java/com/alibaba/testable/core/util/LogUtil.java
+++ b/testable-core/src/main/java/com/alibaba/testable/core/util/LogUtil.java
@@ -50,6 +50,10 @@ public class LogUtil {
         }
     }
 
+    public static void error(String msg, Object... args) {
+        System.err.println(String.format("[FAIL] " + msg, args));
+    }
+
     public static void enableDiagnose(boolean enable) {
         currentLogLevel = enable ? LogLevel.LEVEL_DIAGNOSE : LogLevel.LEVEL_MUTE;
     }