diff --git a/stepper.py b/stepper.py
index 4c95558..ee4f774 100644
--- a/stepper.py
+++ b/stepper.py
@@ -63,12 +63,16 @@ def terminate(terminator, blocks, stack_frames, ssa_env, global_env, memory):
         else:
             oper_v = eval_oper(oper, ssa_env, global_env)
         if len(stack_frames) == 0:
-            return [], None, [], [], ssa_env, memory, oper_v
+            new_insns = []
+            new_terminator = None
+            new_blocks = {}
+            new_ssa_env = ssa_env
+            new_stack_frames = []
         else:
             new_insns, new_terminator, new_blocks, new_ssa_env = stack_frames[0]
             new_stack_frames = stack_frames[1:]
-            return (new_insns, new_terminator, new_blocks, new_stack_frames,
-                    new_ssa_env, memory, oper_v)
+        return (new_insns, new_terminator, new_blocks, new_stack_frames,
+                new_ssa_env, memory, oper_v)
     elif isinstance(terminator, ll.Br):
         label = terminator.label
         next_block = blocks[label]