diff --git a/src/core/org/luaj/vm2/LuaThread.java b/src/core/org/luaj/vm2/LuaThread.java
index aa40b805..1acfcfcf 100644
--- a/src/core/org/luaj/vm2/LuaThread.java
+++ b/src/core/org/luaj/vm2/LuaThread.java
@@ -138,7 +138,7 @@ public class LuaThread extends LuaValue implements Runnable {
 	}
 
 	public static final LuaFunction getCallstackFunction(int level) {
-		return level>=0 || level<running_thread.calls? 
+		return level>0 || level<running_thread.calls? 
 			running_thread.callstack[running_thread.calls-level-1]:
 			null;
 	}