diff --git a/adia/class_.py b/adia/class_.py
index 05f71c4..1f9ac13 100644
--- a/adia/class_.py
+++ b/adia/class_.py
@@ -127,6 +127,7 @@ class diagram section.
 
     def __init__(self, *args, **kwargs):
         super().__init__('title', *args, **kwargs)
+        self._classdict = {}
 
     def __repr__(self):
         return f'ClassDiagram: {self.title or "Untitled"}'
@@ -150,6 +151,26 @@ def dumps(self):
     def _set_title(self, value, *args):
         self.title = value.strip()
 
+    def _complete(self):
+        classdict = {c.title: c for c in self}
+
+        def _ensure_class(title):
+            c = classdict.get(title)
+            if c:
+                return
+
+            c = Class_()
+            c.title = title
+            self.append(c)
+
+        for c in self:
+            for p in c.parents:
+                _ensure_class(p)
+
+            for m in c.members:
+                if m.ref:
+                    _ensure_class(m.ref)
+
     def _new_class(self, class_):
         self.append(class_)
 
@@ -162,7 +183,7 @@ def _new_class(self, class_):
         'start': {
             HASH: {EVERYTHING: {NEWLINE: GoTo('start', ignore=True)}},
             NEWLINE: GoTo('start', ignore=True),
-            EOF: Terminate(),
+            EOF: Terminate(cb=_complete),
             NAME: New(Class_, 'start', cb=_new_class)
         }
     }
diff --git a/adia/renderer.py b/adia/renderer.py
index a6ad3bb..4172359 100644
--- a/adia/renderer.py
+++ b/adia/renderer.py
@@ -797,18 +797,30 @@ class ClassRenderer(BaseRenderer):
     _classplans_dict = None
     _classplans = None
 
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        self._classplans_dict = {}
+        self._classplans = []
+
     def _add_classplan(self, d):
+        if d.title in self._classplans_dict:
+            return
+
         plan = ClassPlan(d)
         self._classplans_dict[d.title] = plan
         self._classplans.append(plan)
 
     def plan(self):
-        self._classplans_dict = {}
-        self._classplans = []
-
         for d in self.diagram:
             self._add_classplan(d)
 
+            # for p in d.parents:
+            #     self._add_classplan(p)
+
+            # for m in d.members:
+            #     if m.ref:
+            #         self._add_classplan(m.ref)
+
     def _autoposition(self):
         col = 0
         row = 0
diff --git a/tests/test_class.py b/tests/test_class.py
index 3d53adc..9839318 100644
--- a/tests/test_class.py
+++ b/tests/test_class.py
@@ -60,3 +60,39 @@ def test_class_position():
     . +-----+ +-----+ .
     ...................
     ''')
+
+
+def test_class_ref():
+    d = Diagram('''
+        class:
+        foo
+          b -> bar
+    ''')
+    assert eqdia(d, '''
+    ...................
+    . +-----+ +-----+ .
+    . | foo | | bar | .
+    . +-----+ +-----+ .
+    . | b   |         .
+    . +-----+         .
+    ...................
+    ''')
+    assert d[0][0].title == 'foo'
+    assert d[0][1].title == 'bar'
+
+
+def test_class_inheritance():
+    d = Diagram('''
+        class:
+        foo(bar, baz)
+    ''')
+    assert eqdia(d, '''
+    ...........................
+    . +-----+ +-----+ +-----+ .
+    . | foo | | bar | | baz | .
+    . +-----+ +-----+ +-----+ .
+    ...........................
+    ''')
+    assert d[0][0].title == 'foo'
+    assert d[0][1].title == 'bar'
+    assert d[0][2].title == 'baz'
diff --git a/tests/test_class_interpreter.py b/tests/test_class_interpreter.py
index 804f003..cb3d8ae 100644
--- a/tests/test_class_interpreter.py
+++ b/tests/test_class_interpreter.py
@@ -95,24 +95,25 @@ def test_class_method():
 
 
 def test_class_reference():
-    s = '''
+    d = class_('''
         class: Foo
 
         foo
           bar -> baz
-    '''
-    eqrepr(s)
-
-    d = class_('''
+    ''')
+    assert len(d) == 2
+    assert eqbigstr(d, '''
         class: Foo
+
         foo
           bar -> baz
+
+        baz
     ''')
-    assert len(d) == 1
 
 
 def test_class_inheritance():
-    s = '''
+    d = class_('''
         class: Foo
 
         foo(bar)
@@ -120,5 +121,15 @@ def test_class_inheritance():
           *Bar bar(int *a)
 
         bar(baz, qux)
-    '''
-    eqrepr(s)
+    ''')
+    assert eqbigstr(d, '''
+        class: Foo
+
+        foo(bar)
+          int bar(a, *b, c)
+          *Bar bar(int *a)
+
+        bar(baz, qux)
+        baz
+        qux
+    ''')