diff --git a/PExpr.h b/PExpr.h
index 3481351aa..7f82b1c6b 100644
--- a/PExpr.h
+++ b/PExpr.h
@@ -474,6 +474,8 @@ class PEUnary : public PExpr {
 
       virtual void dump(ostream&out) const;
 
+      virtual bool elaborate_sig(Design*des, NetScope*scope) const;
+
       virtual NetNet* elaborate_net(Design*des, NetScope*scope,
 				    unsigned width,
 				    const NetExpr* rise,
@@ -533,6 +535,8 @@ class PEBinary : public PExpr {
 				  unsigned min, unsigned lval,
 				  bool&unsized_flag) const;
 
+      virtual bool elaborate_sig(Design*des, NetScope*scope) const;
+
       virtual NetNet* elaborate_net(Design*des, NetScope*scope,
 				    unsigned width,
 				    const NetExpr* rise,
@@ -648,6 +652,8 @@ class PETernary : public PExpr {
 				  unsigned min, unsigned lval,
 				  bool&unsized_flag) const;
 
+      virtual bool elaborate_sig(Design*des, NetScope*scope) const;
+
       virtual NetNet* elaborate_net(Design*des, NetScope*scope,
 				    unsigned width,
 				    const NetExpr* rise,
diff --git a/elab_sig.cc b/elab_sig.cc
index dbbda62a4..95a9fa032 100644
--- a/elab_sig.cc
+++ b/elab_sig.cc
@@ -267,6 +267,28 @@ bool PEIdent::elaborate_sig(Design*des, NetScope*scope) const
       return sig != 0;
 }
 
+bool PEBinary::elaborate_sig(Design*des, NetScope*scope) const
+{
+      bool flag = true;
+
+      flag = left_->elaborate_sig(des, scope)  && flag;
+      flag = right_->elaborate_sig(des, scope) && flag;
+      return flag;
+}
+
+bool PETernary::elaborate_sig(Design*des, NetScope*scope) const
+{
+      bool flag = true;
+      flag = tru_->elaborate_sig(des, scope)  && flag;
+      flag = fal_->elaborate_sig(des, scope)  && flag;
+      return flag;
+}
+
+bool PEUnary::elaborate_sig(Design*des, NetScope*scope) const
+{
+      return expr_->elaborate_sig(des, scope);
+}
+
 bool PGate::elaborate_sig(Design*des, NetScope*scope) const
 {
       return true;