diff --git a/stepper.py b/stepper.py
index 5d11eaa..1592f05 100644
--- a/stepper.py
+++ b/stepper.py
@@ -23,10 +23,10 @@ class Garbage(Enum):
     GARBAGE = '<<Unitialized memory>>'
 
 
-def step(insns, terminator, blocks, stack_frames, ssa_env, global_env, memory,
+def step(insns, terminator, blocks, stack_frames, ssa_env, global_env, heap,
          tdecs, fdecs, call_res):
     if len(insns) == 0:
-        return terminate(terminator, blocks, stack_frames, ssa_env, global_env, memory,
+        return terminate(terminator, blocks, stack_frames, ssa_env, global_env, heap,
                          call_res)
     ssa_target, next_insn = insns[0]
     insns_rest = insns[1:]
@@ -56,9 +56,9 @@ def step(insns, terminator, blocks, stack_frames, ssa_env, global_env, memory,
         print('alloca {}  -->  allocating {} cells'
               .format(ll.ty2s(base_ty), size))
 
-        ptr = len(memory)
+        ptr = len(heap)
         for i in range(max(size, 1)):
-            memory.append(Garbage.GARBAGE)
+            heap.append(Garbage.GARBAGE)
 
         res = ptr
     elif isinstance(next_insn, ll.Load):
@@ -83,7 +83,7 @@ def step(insns, terminator, blocks, stack_frames, ssa_env, global_env, memory,
         if not isinstance(callee, ll.Gid):
             err('Cannot call anything but global identifiers: {}'
                 .format(ll.oper2s(callee)))
-            return insns_rest, terminator, blocks, stack_frames, ssa_env, memory, call_res
+            return insns_rest, terminator, blocks, stack_frames, ssa_env, heap, call_res
 
         arguments_v = [eval_oper(oper, ssa_env, global_env)
                        for ty, oper in arguments]
@@ -93,7 +93,7 @@ def step(insns, terminator, blocks, stack_frames, ssa_env, global_env, memory,
         except KeyError:
             err('Could not find function {} in environment:\n{}'
                 .format(callee.val, fdecs.keys()))
-            return insns_rest, terminator, blocks, stack_frames, ssa_env, memory, call_res
+            return insns_rest, terminator, blocks, stack_frames, ssa_env, heap, call_res
 
         parameters = function.parameters
         print('call @{} ({})'
@@ -105,10 +105,10 @@ def step(insns, terminator, blocks, stack_frames, ssa_env, global_env, memory,
         child_blocks = function.body.named_blocks
         child_stack_frames = [(insns_rest, terminator, blocks, ssa_env)] + stack_frames
         child_ssa_env = {par[1]: arg for par, arg in zip(parameters, arguments_v)}
-        child_memory = memory
+        child_heap = heap
         child_call_res = [ssa_target] + call_res
         return (child_insns, child_terminator, child_blocks, child_stack_frames,
-                child_ssa_env, child_memory, child_call_res)
+                child_ssa_env, child_heap, child_call_res)
 
     elif isinstance(next_insn, ll.Bitcast):
         oper = next_insn.oper
@@ -161,10 +161,10 @@ def step(insns, terminator, blocks, stack_frames, ssa_env, global_env, memory,
                   .format(ssa_target, res))
             ssa_env[ssa_target] = res
 
-    return insns_rest, terminator, blocks, stack_frames, ssa_env, memory, call_res
+    return insns_rest, terminator, blocks, stack_frames, ssa_env, heap, call_res
 
 
-def terminate(terminator, blocks, stack_frames, ssa_env, global_env, memory, call_res):
+def terminate(terminator, blocks, stack_frames, ssa_env, global_env, heap, call_res):
     def clear_block_from_ssa_env(insns, ssa_env):
         for (id, insn) in insns:
             if id is not None and id in ssa_env:
@@ -197,7 +197,7 @@ def terminate(terminator, blocks, stack_frames, ssa_env, global_env, memory, cal
             new_stack_frames = stack_frames[1:]
             new_call_res = call_res[1:]
         return (new_insns, new_terminator, new_blocks, new_stack_frames,
-                new_ssa_env, memory, new_call_res)
+                new_ssa_env, heap, new_call_res)
     elif isinstance(terminator, ll.Br):
         label = terminator.label
         next_block = blocks[label]
@@ -214,7 +214,7 @@ def terminate(terminator, blocks, stack_frames, ssa_env, global_env, memory, cal
               .format(label))
 
         return (new_insns, new_terminator, blocks, stack_frames,
-                ssa_env, memory, call_res)
+                ssa_env, heap, call_res)
     elif isinstance(terminator, ll.Cbr):
         ty = terminator.ty
         if ty != ll.SimpleType.I1:
@@ -238,7 +238,7 @@ def terminate(terminator, blocks, stack_frames, ssa_env, global_env, memory, cal
               .format(operand_v, label))
 
         return (new_insns, new_terminator, blocks, stack_frames,
-                ssa_env, memory, call_res)
+                ssa_env, heap, call_res)
     else:
         err('Unknown LLVM terminator: {}'
             .format(terminator))
@@ -353,15 +353,15 @@ define i64 @tigermain (i64 %U_mainSL_8, i64 %U_mainDummy_9) {
     stack_frames = []
     ssa_env = {}
     # TODO: memory structure has not been decided yet
-    memory = [None]
+    heap = [None]
     call_res = []
 
     while True:
         (insns, terminator, blocks,
-         stack_frames, ssa_env, memory, call_res) = step(insns, terminator, blocks,
-                                                         stack_frames, ssa_env,
-                                                         global_env, memory, tdecs,
-                                                         fdecs, call_res)
+         stack_frames, ssa_env, heap, call_res) = step(insns, terminator, blocks,
+                                                       stack_frames, ssa_env,
+                                                       global_env, heap, tdecs,
+                                                       fdecs, call_res)
 
         if terminator is None:
             print('Stepping done! Final ssa_env:\n{}'