diff --git a/src/V3Ast.h b/src/V3Ast.h
index f3dda1661..5917f1724 100644
--- a/src/V3Ast.h
+++ b/src/V3Ast.h
@@ -26,6 +26,7 @@
 #include "verilatedos.h"
 #include "V3Error.h"
 #include "V3Number.h"
+#include "V3Global.h"
 #include <vector>
 #include <cmath>
 
diff --git a/src/V3Global.h b/src/V3Global.h
index 21e47816b..16e2139ed 100644
--- a/src/V3Global.h
+++ b/src/V3Global.h
@@ -29,7 +29,8 @@
 
 #include "V3Error.h"
 #include "V3Options.h"
-#include "V3Ast.h"
+
+class AstNetlist;
 
 //======================================================================
 // Statics
@@ -54,23 +55,22 @@ public:
   public:
     // CREATORS
     V3Global() {
-	m_rootp = new AstNetlist;
 	m_debugFileNumber = 0;
 	m_assertWidthsSame = false;
 	m_needHInlines = false;
 	m_needHeavy = false;
 	m_dpi = false;
+	m_rootp = makeNetlist();
     }
-    void clear() {
-	if (m_rootp) m_rootp->deleteTree(); m_rootp=NULL;
-    }
+    AstNetlist* makeNetlist();
+    void clear();
     // ACCESSORS (general)
     AstNetlist* rootp() const { return m_rootp; }
     bool assertWidthsSame() const { return m_assertWidthsSame; }
 
     // METHODS
     void readFiles();
-    void checkTree() { rootp()->checkTree(); }
+    void checkTree();
     void assertWidthsSame(bool flag) { m_assertWidthsSame = flag; }
     string debugFilename(const string& nameComment, int newNumber=0) {
 	++m_debugFileNumber;
diff --git a/src/V3Graph.h b/src/V3Graph.h
index b91827b8f..548720951 100644
--- a/src/V3Graph.h
+++ b/src/V3Graph.h
@@ -26,6 +26,7 @@
 #include "verilatedos.h"
 #include "V3Error.h"
 #include "V3List.h"
+#include "V3Ast.h"
 #include <vector>
 #include <algorithm>
 
diff --git a/src/V3SymTable.h b/src/V3SymTable.h
index 1775a31a1..acf792678 100644
--- a/src/V3SymTable.h
+++ b/src/V3SymTable.h
@@ -32,6 +32,7 @@
 #include <iomanip>
 
 #include "V3Global.h"
+#include "V3Ast.h"
 
 //######################################################################
 // Symbol table
diff --git a/src/Verilator.cpp b/src/Verilator.cpp
index 13ab8bdaa..e27e13401 100644
--- a/src/Verilator.cpp
+++ b/src/Verilator.cpp
@@ -94,6 +94,13 @@ V3Global v3Global;
 //######################################################################
 // V3 Class -- top level
 
+AstNetlist* V3Global::makeNetlist() { return new AstNetlist(); }
+void V3Global::checkTree() { rootp()->checkTree(); }
+
+void V3Global::clear() {
+    if (m_rootp) m_rootp->deleteTree(); m_rootp=NULL;
+}
+
 void V3Global::readFiles() {
     // NODE STATE
     //   AstNode::user4p()	// V3SymTable*    Package and typedef symbol names