diff --git a/src/V3Const.cpp b/src/V3Const.cpp
index a4a0e7fc7..8353833e2 100644
--- a/src/V3Const.cpp
+++ b/src/V3Const.cpp
@@ -41,6 +41,14 @@
 
 VL_DEFINE_DEBUG_FUNCTIONS;
 
+#define TREE_SKIP_VISIT(...)
+#define TREEOP1(...)
+#define TREEOPA(...)
+#define TREEOP(...)
+#define TREEOPS(...)
+#define TREEOPC(...)
+#define TREEOPV(...)
+
 //######################################################################
 // Utilities
 
diff --git a/src/astgen b/src/astgen
index 1be8dff1c..cf247a544 100755
--- a/src/astgen
+++ b/src/astgen
@@ -245,8 +245,8 @@ class Cpt:
                     self.output_func(lambda self: self._output_line())
                     self.tree_line(func)
                     didln = False
-                elif not re.match(r'^\s*/[/\*]\s*TREE', line) and re.search(
-                        r'\s+TREE', line):
+                elif not re.match(r'^\s*(#define|/[/\*])\s*TREE',
+                                  line) and re.search(r'\s+TREE', line):
                     self.error("Unknown astgen line: " + line)
                 else:
                     self.print(line)