diff --git a/capgen/generator/group_cap.py b/capgen/generator/group_cap.py
index a6e0069d..a66c202a 100644
--- a/capgen/generator/group_cap.py
+++ b/capgen/generator/group_cap.py
@@ -33,6 +33,7 @@
     ResolvedCall,
     ResolvedGroup,
     ResolvedSubcycle,
+    _render_value_expr,
     _root_symbol,
     iter_phase_calls,
     iter_phase_subcycles,
@@ -179,7 +180,12 @@ def _dim_decl_local(dimensions: List[str], host_dict) -> str:
             locals_.append('{}:{}'.format(lb, ub))
         else:
             entry = host_dict.get(std_name) if host_dict else None
-            locals_.append(entry.local_name if entry is not None else std_name)
+            # ``access_path``, not ``local_name`` so that a DDT-component dimension
+            # (``GFS_Control%levs`` for ``vertical_layer_dimension``) is resolved.
+            locals_.append(
+                _render_value_expr(entry, host_dict)
+                if entry is not None else std_name
+            )
     return ', dimension({})'.format(', '.join(locals_))
 
 
diff --git a/unit-tests/test_suite_resolver.py b/unit-tests/test_suite_resolver.py
index 86cd98e5..84ffb102 100644
--- a/unit-tests/test_suite_resolver.py
+++ b/unit-tests/test_suite_resolver.py
@@ -2693,12 +2693,31 @@ def test_horizontal_dimension_uses_chunk_bounds(self):
         )
 
     def test_vertical_dim_uses_local_name(self):
-        # No special case for vertical dims — host's local name only.
+        # No special case for vertical dims.  For a plain module-level host
+        # var the access path and the local name are the same string.
         self.assertEqual(
             _dim_decl_local(['vertical_layer_dimension'], self.hd),
             ', dimension(nlev)',
         )
 
+    def test_ddt_component_dim_uses_full_access_path(self):
+        """A DDT-component dimension must be declared with the full DDT
+        walk.  ``local_name`` alone (``levs``) names nothing in the group
+        cap's scope, so the temp is sized from an undefined symbol — the
+        transform's assignments were right and only its declaration wrong."""
+        from metadata.variable_resolver import HostVarEntry
+        hd = dict(self.hd)
+        hd['vertical_layer_dimension'] = HostVarEntry(
+            'vertical_layer_dimension', 'levs', 'GFS_Control%levs',
+            None, 'integer', '', 'count', [], False, False, '',
+        )
+        self.assertEqual(
+            _dim_decl_local(
+                ['horizontal_dimension', 'vertical_layer_dimension'], hd,
+            ),
+            ', dimension(lb:ub, GFS_Control%levs)',
+        )
+
     def test_mixed_horiz_vert(self):
         self.assertEqual(
             _dim_decl_local(