diff --git a/elab_expr.cc b/elab_expr.cc
index 11ac12dcc..8b322831b 100644
--- a/elab_expr.cc
+++ b/elab_expr.cc
@@ -2148,8 +2148,8 @@ unsigned PETernary::test_width(Design*des, NetScope*scope,
       return max(tru_wid,fal_wid);
 }
 
-static bool test_ternary_operand_compat(ivl_variable_type_t l,
-					ivl_variable_type_t r)
+bool NetETernary::test_operand_compat(ivl_variable_type_t l,
+				      ivl_variable_type_t r)
 {
       if (l == IVL_VT_LOGIC && r == IVL_VT_BOOL)
 	    return true;
@@ -2245,7 +2245,7 @@ NetExpr*PETernary::elaborate_expr(Design*des, NetScope*scope,
 	    return 0;
       }
 
-      if (! test_ternary_operand_compat(tru->expr_type(), fal->expr_type())) {
+      if (! NetETernary::test_operand_compat(tru->expr_type(), fal->expr_type())) {
 	    cerr << get_fileline() << ": error: Data types "
 		 << tru->expr_type() << " and "
 		 << fal->expr_type() << " of ternary"
diff --git a/expr_synth.cc b/expr_synth.cc
index 28f6d449f..2ac96bbfb 100644
--- a/expr_synth.cc
+++ b/expr_synth.cc
@@ -746,7 +746,7 @@ NetNet* NetEConst::synthesize(Design*des, NetScope*scope)
 
       NetNet*osig = new NetNet(scope, path, NetNet::IMPLICIT, width-1,0);
       osig->local_flag(true);
-      osig->data_type(IVL_VT_LOGIC);
+      osig->data_type(expr_type());
       osig->set_signed(has_sign());
       NetConst*con = new NetConst(scope, scope->local_symbol(), value());
       connect(osig->pin(0), con->pin(0));
@@ -1097,13 +1097,18 @@ NetNet* NetETernary::synthesize(Design *des, NetScope*scope)
 
       if (csig == 0 || tsig == 0 || fsig == 0) return 0;
 
-      if (tsig->data_type() != fsig->data_type()) {
-	    cerr << get_fileline() << ": error: True and False clauses of "
-	            "ternary expression have different types." << endl;
+      if (! NetETernary::test_operand_compat(tsig->data_type(),fsig->data_type())) {
+	    cerr << get_fileline() << ": internal error: "
+		 << " True and False clauses of ternary expression "
+		 << " have incompatible types." << endl;
 	    cerr << get_fileline() << ":      : True  clause is: "
-	         << tsig->data_type() << endl;
+	         << tsig->data_type()
+		 << " (" << true_val_->expr_type() << "): "
+		 << *true_val_ << endl;
 	    cerr << get_fileline() << ":      : False clause is: "
-	         << fsig->data_type() << endl;
+	         << fsig->data_type()
+		 << " (" << false_val_->expr_type() << "): "
+		 << *false_val_ << endl;
 	    des->errors += 1;
 	    return 0;
       } else if (tsig->data_type() == IVL_VT_NO_TYPE) {
diff --git a/ivl_target.h b/ivl_target.h
index 58c27e424..159ff7dac 100644
--- a/ivl_target.h
+++ b/ivl_target.h
@@ -502,7 +502,8 @@ extern ivl_net_const_t ivl_design_const(ivl_design_t, unsigned idx);
  * ivl_const_bits
  *    This returns a pointer to an array of constant characters,
  *    each byte a '0', '1', 'x' or 'z'. The array is *not* nul
- *    terminated.
+ *    terminated. This value is only value if ivl_const_type is
+ *    IVL_VT_LOGIC or IVL_VT_BOOL. It returns nil otherwise.
  *
  * ivl_const_nex
  *    Return the ivl_nexus_t of the output for the constant.
diff --git a/netlist.h b/netlist.h
index 931b9fe74..65d803ccb 100644
--- a/netlist.h
+++ b/netlist.h
@@ -3565,6 +3565,9 @@ class NetETernary  : public NetExpr {
       virtual void dump(ostream&) const;
       virtual NetNet*synthesize(Design*, NetScope*scope);
 
+    public:
+      static bool test_operand_compat(ivl_variable_type_t tru, ivl_variable_type_t fal);
+
     private:
       NetExpr*cond_;
       NetExpr*true_val_;
diff --git a/t-dll-api.cc b/t-dll-api.cc
index d5ab959ea..c68a61f32 100644
--- a/t-dll-api.cc
+++ b/t-dll-api.cc
@@ -118,6 +118,7 @@ extern "C" const char*ivl_const_bits(ivl_net_const_t net)
       assert(net);
       switch (net->type) {
 
+	  case IVL_VT_BOOL:
 	  case IVL_VT_LOGIC:
 	    if (net->width_ <= sizeof(net->b.bit_))
 		  return net->b.bit_;
diff --git a/t-dll.cc b/t-dll.cc
index d09536f01..d41359bbd 100644
--- a/t-dll.cc
+++ b/t-dll.cc
@@ -2199,7 +2199,7 @@ bool dll_target::net_const(const NetConst*net)
 
       struct ivl_net_const_s *obj = new struct ivl_net_const_s;
 
-      obj->type = IVL_VT_LOGIC;
+      obj->type = IVL_VT_BOOL;
 
 	/* constants have a single vector output. */
       assert(net->pin_count() == 1);
@@ -2223,9 +2223,13 @@ bool dll_target::net_const(const NetConst*net)
 		  bits[idx] = '1';
 		  break;
 		case verinum::Vx:
+		  if (obj->type == IVL_VT_BOOL)
+			obj->type = IVL_VT_LOGIC;
 		  bits[idx] = 'x';
 		  break;
 		case verinum::Vz:
+		  if (obj->type == IVL_VT_BOOL)
+			obj->type = IVL_VT_LOGIC;
 		  bits[idx] = 'z';
 		  break;
 	    }
diff --git a/tgt-stub/stub.c b/tgt-stub/stub.c
index 13da6f4d2..21c27df08 100644
--- a/tgt-stub/stub.c
+++ b/tgt-stub/stub.c
@@ -1058,8 +1058,10 @@ static void signal_nexus_const(ivl_signal_t sig,
       fprintf(out, "      const-");
 
       switch (ivl_const_type(con)) {
+	  case IVL_VT_BOOL:
 	  case IVL_VT_LOGIC:
 	    bits = ivl_const_bits(con);
+	    assert(bits);
 	    for (idx = 0 ;  idx < width ;  idx += 1) {
 		  fprintf(out, "%c", bits[width-idx-1]);
 	    }