--- a/src/luan/modules/ThreadLuan.java	Wed Feb 07 23:16:12 2018 -0700
+++ b/src/luan/modules/ThreadLuan.java	Thu Feb 08 02:22:51 2018 -0700
@@ -1,6 +1,7 @@
 package luan.modules;
 
 import java.io.Closeable;
+import java.util.Arrays;
 import java.util.Iterator;
 import java.util.Map;
 import java.util.HashMap;
@@ -140,7 +141,7 @@
 
 		public synchronized Object call(String fnName,Object... args) throws LuanException {
 			if( !isPrimitive(args) )
-				throw new LuanException("can't pass non-primitive type to global_callable");
+				throw new LuanException("can't pass non-primitive type to global_callable "+Arrays.asList(args));
 			Object f = fns.get(luan,fnName);
 			if( f == null )
 				throw new LuanException("function '"+fnName+"' not found in global_callable");