diff --git a/nasal_gc.h b/nasal_gc.h
index 3240bd7..0e5964e 100644
--- a/nasal_gc.h
+++ b/nasal_gc.h
@@ -307,8 +307,6 @@ int nasal_hash::get_value_address(std::string key)
             }
         }
     }
-    else
-        std::cout<<">> [runtime] cannot find hash member \""<<key<<"\".\n";
     return ret_value_addr;
 }
 int nasal_hash::get_mem_address(std::string key)
@@ -334,13 +332,6 @@ int nasal_hash::get_mem_address(std::string key)
             }
         }
     }
-    else
-    {
-        int val_addr=vm.gc_alloc(vm_nil);
-        int mem_addr=vm.mem_alloc(val_addr);
-        elems[key]=mem_addr;
-        ret_mem_addr=mem_addr;
-    }
     return ret_mem_addr;
 }
 bool nasal_hash::check_contain(std::string key)
@@ -656,12 +647,10 @@ nasal_virtual_machine::~nasal_virtual_machine()
         {
             garbage_collector_memory[i]->ref_cnt=0;
             garbage_collector_memory[i]->collected=true;
+            garbage_collector_memory[i]->elem.clear();
         }
     for(int i=0;i<gc_mem_size;++i)
-    {
-        garbage_collector_memory[i]->elem.clear();
         delete garbage_collector_memory[i];
-    }
     while(!garbage_collector_free_space.empty())
         garbage_collector_free_space.pop();
     while(!memory_manager_free_space.empty())
@@ -699,12 +688,10 @@ void nasal_virtual_machine::clear()
         {
             garbage_collector_memory[i]->ref_cnt=0;
             garbage_collector_memory[i]->collected=true;
+            garbage_collector_memory[i]->elem.clear();
         }
     for(int i=0;i<gc_mem_size;++i)
-    {
-        garbage_collector_memory[i]->elem.clear();
         delete garbage_collector_memory[i];
-    }
     while(!garbage_collector_free_space.empty())
         garbage_collector_free_space.pop();
     while(!memory_manager_free_space.empty())
diff --git a/nasal_runtime.h b/nasal_runtime.h
index 16a88be..dd32fd2 100644
--- a/nasal_runtime.h
+++ b/nasal_runtime.h
@@ -770,7 +770,13 @@ int nasal_runtime::call_hash(nasal_ast& node,int base_value_addr,int local_scope
         die(node.get_line(),"called a value that is not a hash");
         return -1;
     }
-    int ret_value_addr=nasal_vm.gc_get(base_value_addr).get_hash().get_value_address(node.get_str());
+    std::string str=node.get_str();
+    int ret_value_addr=nasal_vm.gc_get(base_value_addr).get_hash().get_value_address(str);
+    if(ret_value_addr<0)
+    {
+        die(node.get_line(),"cannot find member named \""+str+"\"");
+        return -1;
+    }
     nasal_vm.add_reference(ret_value_addr);
     return ret_value_addr;
 }
@@ -1073,7 +1079,13 @@ int nasal_runtime::call_hash_mem(nasal_ast& node,int base_mem_addr,int local_sco
         die(node.get_line(),"called a value that is not a hash");
         return -1;
     }
-    int ret_mem_addr=nasal_vm.gc_get(base_value_addr).get_hash().get_mem_address(node.get_str());
+    nasal_hash& ref=nasal_vm.gc_get(base_value_addr).get_hash();
+    int ret_mem_addr=ref.get_mem_address(node.get_str());
+    if(ret_mem_addr<0)
+    {
+        ref.add_elem(node.get_str(),nasal_vm.gc_alloc(vm_nil));
+        ret_mem_addr=ref.get_mem_address(node.get_str());
+    }
     return ret_mem_addr;
 }
 int nasal_runtime::nasal_scalar_add(int a_scalar_addr,int b_scalar_addr)