diff --git a/loopy/preprocess.py b/loopy/preprocess.py
index ced1aaaa13ed8275c1e3a376d1c24895287b3239..ab6865f5f1d5927a7e6ca7c3411ba898d1f35291 100644
--- a/loopy/preprocess.py
+++ b/loopy/preprocess.py
@@ -162,12 +162,10 @@ def find_temporary_scope(kernel):
 
     base_storage_to_aliases = {}
 
-    kernel_var_names = kernel.all_variable_names(include_temp_storage=False)
-
     for temp_var in six.itervalues(kernel.temporary_variables):
         if temp_var.base_storage is not None:
             # no nesting allowed
-            if temp_var.base_storage in kernel_var_names:
+            if temp_var.base_storage in kernel.temporary_variables:
                 raise LoopyError("base_storage for temporary '%s' is '%s', "
                         "which is an existing variable name"
                         % (temp_var.name, temp_var.base_storage))
diff --git a/loopy/target/c/__init__.py b/loopy/target/c/__init__.py
index a2ad682505bbdb7ed5977a28e201ebc6655c7784..841602b3120b84b3d0df1966989cfe9c763fa7cf 100644
--- a/loopy/target/c/__init__.py
+++ b/loopy/target/c/__init__.py
@@ -439,20 +439,21 @@ class CASTBuilder(ASTBuilderBase):
                 assert tv.initializer is None
 
                 offset = 0
-                base_storage_sizes.setdefault(tv.base_storage, []).append(
-                        tv.nbytes)
-                base_storage_to_scope.setdefault(tv.base_storage, []).append(
-                        tv.scope)
+                if tv.base_storage not in kernel.arg_dict:
+                    base_storage_sizes.setdefault(tv.base_storage, []).append(
+                            tv.nbytes)
+                    base_storage_to_scope.setdefault(tv.base_storage, []).append(
+                            tv.scope)
 
-                align_size = tv.dtype.itemsize
+                    align_size = tv.dtype.itemsize
 
-                from loopy.kernel.array import VectorArrayDimTag
-                for dim_tag, axis_len in zip(tv.dim_tags, tv.shape):
-                    if isinstance(dim_tag, VectorArrayDimTag):
-                        align_size *= axis_len
+                    from loopy.kernel.array import VectorArrayDimTag
+                    for dim_tag, axis_len in zip(tv.dim_tags, tv.shape):
+                        if isinstance(dim_tag, VectorArrayDimTag):
+                            align_size *= axis_len
 
-                base_storage_to_align_bytes.setdefault(tv.base_storage, []).append(
-                        align_size)
+                    base_storage_to_align_bytes.setdefault(tv.base_storage,
+                                                           []).append(align_size)
 
                 for idi in decl_info:
                     cast_decl = POD(self, idi.dtype, "")