diff --git a/src/V3AstNodes.h b/src/V3AstNodes.h
index fe95b13e6..daf17d877 100644
--- a/src/V3AstNodes.h
+++ b/src/V3AstNodes.h
@@ -32,7 +32,7 @@
 
 #define ASTNODE_NODE_FUNCS(name,ucname)	\
     virtual ~Ast ##name() {} \
-    virtual AstType type() const { return AstType:: ucname; } \
+    virtual AstType type() const { return AstType::at ##ucname; } \
     virtual AstNode* clone() { return new Ast ##name (*this); } \
     virtual void accept(AstNVisitor& v, AstNUser* vup=NULL) { v.visit(this,vup); } \
     Ast ##name * cloneTree(bool cloneNext) { return AstNode::cloneTree(cloneNext)->cast ##name(); }
diff --git a/src/V3EmitC.cpp b/src/V3EmitC.cpp
index 7370c4bef..ddbede2fa 100644
--- a/src/V3EmitC.cpp
+++ b/src/V3EmitC.cpp
@@ -1346,7 +1346,7 @@ void EmitCImp::emitCtorImp(AstNodeModule* modp) {
     emitCellCtors(modp);
     emitSensitives();
     emitVarResets(modp);
-    emitTextSection(AstType::SCCTOR);
+    emitTextSection(AstType::atSCCTOR);
     if (optSystemPerl()) puts("SP_AUTO_CTOR;\n");
     puts("}\n");
 }
@@ -1395,7 +1395,7 @@ void EmitCImp::emitCoverageImp(AstNodeModule* modp) {
 void EmitCImp::emitDestructorImp(AstNodeModule* modp) {
     puts("\n");
     puts(modClassName(modp)+"::~"+modClassName(modp)+"() {\n");
-    emitTextSection(AstType::SCDTOR);
+    emitTextSection(AstType::atSCDTOR);
     if (modp->isTop()) puts("delete __VlSymsp; __VlSymsp=NULL;\n");
     puts("}\n");
 }
@@ -1622,7 +1622,7 @@ void EmitCImp::emitInt(AstNodeModule* modp) {
     }
 
     puts("\n//----------\n\n");
-    emitTextSection(AstType::SCHDR);
+    emitTextSection(AstType::atSCHDR);
 
     if (optSystemC() && modp->isTop()) {
 	puts("SC_MODULE("+modClassName(modp)+") {\n");
@@ -1728,7 +1728,7 @@ void EmitCImp::emitInt(AstNodeModule* modp) {
 
     puts("\n// USER METHODS\n");
     if (optSystemPerl()) puts("/*AUTOMETHODS*/\n");
-    emitTextSection(AstType::SCINT);
+    emitTextSection(AstType::atSCINT);
 
     puts("\n// API METHODS\n");
     if (modp->isTop()) {
@@ -1791,7 +1791,7 @@ void EmitCImp::emitImp(AstNodeModule* modp) {
 	puts("SP_MODULE_CONTINUED("+modClassName(modp)+");\n");
     }
 
-    emitTextSection(AstType::SCIMPHDR);
+    emitTextSection(AstType::atSCIMPHDR);
 
     if (m_slow && splitFilenum()==0) {
 	puts("\n//--------------------\n");
@@ -1800,7 +1800,7 @@ void EmitCImp::emitImp(AstNodeModule* modp) {
     }
 
     if (m_fast && splitFilenum()==0) {
-	emitTextSection(AstType::SCIMP);
+	emitTextSection(AstType::atSCIMP);
 	emitStaticDecl(modp);
     }
 
diff --git a/src/V3Signed.cpp b/src/V3Signed.cpp
index 61300961f..b6776dbbd 100644
--- a/src/V3Signed.cpp
+++ b/src/V3Signed.cpp
@@ -303,21 +303,21 @@ private:
 	    AstNode* newp = NULL;
 	    // Given a signed/unsigned node type, create the opposite type
 	    switch (nodep->type()) {
-	    case AstType::GT:	   newp = new AstGtS	(nodep->fileline(), lhsp, rhsp); break;
-	    case AstType::GTS:	   newp = new AstGt	(nodep->fileline(), lhsp, rhsp); break;
-	    case AstType::GTE:	   newp = new AstGteS	(nodep->fileline(), lhsp, rhsp); break;
-	    case AstType::GTES:	   newp = new AstGte	(nodep->fileline(), lhsp, rhsp); break;
-	    case AstType::LT:	   newp = new AstLtS	(nodep->fileline(), lhsp, rhsp); break;
-	    case AstType::LTS:	   newp = new AstLt	(nodep->fileline(), lhsp, rhsp); break;
-	    case AstType::LTE:	   newp = new AstLteS	(nodep->fileline(), lhsp, rhsp); break;
-	    case AstType::LTES:	   newp = new AstLte	(nodep->fileline(), lhsp, rhsp); break;
-	    case AstType::DIV:	   newp = new AstDivS	(nodep->fileline(), lhsp, rhsp); break;
-	    case AstType::DIVS:	   newp = new AstDiv	(nodep->fileline(), lhsp, rhsp); break;
-	    case AstType::MODDIV:  newp = new AstModDivS(nodep->fileline(), lhsp, rhsp); break;
-	    case AstType::MODDIVS: newp = new AstModDiv (nodep->fileline(), lhsp, rhsp); break;
-	    case AstType::MUL:	   newp = new AstMulS	(nodep->fileline(), lhsp, rhsp); break;
-	    case AstType::MULS:	   newp = new AstMul	(nodep->fileline(), lhsp, rhsp); break;
-	    case AstType::SHIFTRS: newp = new AstShiftR	(nodep->fileline(), lhsp, rhsp); break;
+	    case AstType::atGT:		newp = new AstGtS	(nodep->fileline(), lhsp, rhsp); break;
+	    case AstType::atGTS:	newp = new AstGt	(nodep->fileline(), lhsp, rhsp); break;
+	    case AstType::atGTE:	newp = new AstGteS	(nodep->fileline(), lhsp, rhsp); break;
+	    case AstType::atGTES:	newp = new AstGte	(nodep->fileline(), lhsp, rhsp); break;
+	    case AstType::atLT:		newp = new AstLtS	(nodep->fileline(), lhsp, rhsp); break;
+	    case AstType::atLTS:	newp = new AstLt	(nodep->fileline(), lhsp, rhsp); break;
+	    case AstType::atLTE:	newp = new AstLteS	(nodep->fileline(), lhsp, rhsp); break;
+	    case AstType::atLTES:	newp = new AstLte	(nodep->fileline(), lhsp, rhsp); break;
+	    case AstType::atDIV:	newp = new AstDivS	(nodep->fileline(), lhsp, rhsp); break;
+	    case AstType::atDIVS:	newp = new AstDiv	(nodep->fileline(), lhsp, rhsp); break;
+	    case AstType::atMODDIV:	newp = new AstModDivS	(nodep->fileline(), lhsp, rhsp); break;
+	    case AstType::atMODDIVS: 	newp = new AstModDiv 	(nodep->fileline(), lhsp, rhsp); break;
+	    case AstType::atMUL:	newp = new AstMulS	(nodep->fileline(), lhsp, rhsp); break;
+	    case AstType::atMULS:	newp = new AstMul	(nodep->fileline(), lhsp, rhsp); break;
+	    case AstType::atSHIFTRS:	newp = new AstShiftR	(nodep->fileline(), lhsp, rhsp); break;
 	    default:
 		nodep->v3fatalSrc("Node needs sign change, but bad case: "<<nodep<<endl);
 		break;
diff --git a/src/astgen b/src/astgen
index 332d34606..c6fe0ed25 100755
--- a/src/astgen
+++ b/src/astgen
@@ -157,9 +157,10 @@ sub write_types {
     my $fh = open_file(@_);
 
     printf $fh "    enum en {\n";
+    # Add "at" prefix to avoid conflicting with FOPEN and other macros in include files
     foreach my $type (sort (keys %Classes)) {
 	next if $type =~ /^Node/;
-	print $fh "\t",uc $type,",\n";
+	print $fh "\tat",uc $type,",\n";
     }
     printf $fh "\t_ENUM_END\n";
     printf $fh "    };\n";
diff --git a/test_vcs/Makefile b/test_vcs/Makefile
index 272336c9f..58bf30fdf 100644
--- a/test_vcs/Makefile
+++ b/test_vcs/Makefile
@@ -48,7 +48,7 @@ novcs:
 vcs:	vcs_passed.log
 
 simv:	$(V_FILES) ../test_v/input.vc
-	vcs +cli -I +define+vcs+1 -f ../test_v/input.vc -q bench.v
+	vcs +cli -I -sverilog +define+VCS+1 -f ../test_v/input.vc -q bench.v
 
 vcs_passed.log	: simv
 	-rm -f test_passed.log