diff --git a/tgt-vhdl/expr.cc b/tgt-vhdl/expr.cc
index f64ac4ac6..9e383dfc9 100644
--- a/tgt-vhdl/expr.cc
+++ b/tgt-vhdl/expr.cc
@@ -149,6 +149,9 @@ static vhdl_expr *translate_unary(ivl_expr_t e)
    case '~':
       return new vhdl_unaryop_expr
          (VHDL_UNARYOP_NOT, operand, new vhdl_type(*operand->get_type()));
+   case '-':
+      return new vhdl_unaryop_expr
+         (VHDL_UNARYOP_NEG, operand, new vhdl_type(*operand->get_type()));
    case 'N':   // NOR
       return translate_reduction(SF_REDUCE_OR, true, operand);
    case '|':
diff --git a/tgt-vhdl/vhdl_syntax.cc b/tgt-vhdl/vhdl_syntax.cc
index 3cc70853a..a14f11e6d 100644
--- a/tgt-vhdl/vhdl_syntax.cc
+++ b/tgt-vhdl/vhdl_syntax.cc
@@ -657,6 +657,9 @@ void vhdl_unaryop_expr::emit(std::ostream &of, int level) const
    case VHDL_UNARYOP_NOT:
       of << "not ";
       break;
+   case VHDL_UNARYOP_NEG:
+      of << "-";
+      break;
    }
    operand_->emit(of, level);
    of << ")";
diff --git a/tgt-vhdl/vhdl_syntax.hh b/tgt-vhdl/vhdl_syntax.hh
index fcf06286a..c6a2c727f 100644
--- a/tgt-vhdl/vhdl_syntax.hh
+++ b/tgt-vhdl/vhdl_syntax.hh
@@ -107,6 +107,7 @@ private:
 
 enum vhdl_unaryop_t {
    VHDL_UNARYOP_NOT,
+   VHDL_UNARYOP_NEG,
 };
 
 class vhdl_unaryop_expr : public vhdl_expr {