diff --git a/vhdlpp/expression.cc b/vhdlpp/expression.cc
index 9efe60931..1ecd867f5 100644
--- a/vhdlpp/expression.cc
+++ b/vhdlpp/expression.cc
@@ -818,6 +818,15 @@ ExpUNot::~ExpUNot()
 {
 }
 
+ExpUMinus::ExpUMinus(Expression*op1)
+: ExpUnary(op1)
+{
+}
+
+ExpUMinus::~ExpUMinus()
+{
+}
+
 ExpCast::ExpCast(Expression*base, const VType*type) :
     base_(base), type_(type)
 {
diff --git a/vhdlpp/expression.h b/vhdlpp/expression.h
index 65e1934bd..ca895967e 100644
--- a/vhdlpp/expression.h
+++ b/vhdlpp/expression.h
@@ -948,6 +948,19 @@ class ExpUNot : public ExpUnary {
       void dump(ostream&out, int indent = 0) const;
 };
 
+class ExpUMinus : public ExpUnary {
+
+    public:
+      explicit ExpUMinus(Expression*op1);
+      ~ExpUMinus();
+
+      Expression*clone() const { return new ExpUMinus(peek_operand()->clone()); }
+
+      void write_to_stream(std::ostream&fd) const;
+      int emit(ostream&out, Entity*ent, ScopeBase*scope) const;
+      void dump(ostream&out, int indent = 0) const;
+};
+
 /*
  * Class that wraps other expressions to cast them to other types.
  */
diff --git a/vhdlpp/expression_debug.cc b/vhdlpp/expression_debug.cc
index f745f128d..cf6a46902 100644
--- a/vhdlpp/expression_debug.cc
+++ b/vhdlpp/expression_debug.cc
@@ -142,6 +142,12 @@ void ExpUNot::dump(ostream&out, int indent) const
       dump_operand1(out, indent+4);
 }
 
+void ExpUMinus::dump(ostream&out, int indent) const
+{
+      out << setw(indent) << "" << "unary_minus() at " << get_fileline() << endl;
+      dump_operand1(out, indent+4);
+}
+
 void ExpTime::dump(ostream&out, int indent) const
 {
       out << setw(indent) << "" << "Time ";
diff --git a/vhdlpp/expression_emit.cc b/vhdlpp/expression_emit.cc
index f490cf4dd..e3c6cb964 100644
--- a/vhdlpp/expression_emit.cc
+++ b/vhdlpp/expression_emit.cc
@@ -1048,6 +1048,15 @@ int ExpUNot::emit(ostream&out, Entity*ent, ScopeBase*scope) const
       return errors;
 }
 
+int ExpUMinus::emit(ostream&out, Entity*ent, ScopeBase*scope) const
+{
+      int errors = 0;
+      out << "-(";
+      errors += emit_operand1(out, ent, scope);
+      out << ")";
+      return errors;
+}
+
 int ExpCast::emit(ostream&out, Entity*ent, ScopeBase*scope) const
 {
       int errors = 0;
diff --git a/vhdlpp/expression_stream.cc b/vhdlpp/expression_stream.cc
index 43756922a..f9f6f40e5 100644
--- a/vhdlpp/expression_stream.cc
+++ b/vhdlpp/expression_stream.cc
@@ -327,6 +327,13 @@ void ExpUNot::write_to_stream(ostream&fd) const
       write_to_stream_operand1(fd);
 }
 
+void ExpUMinus::write_to_stream(ostream&fd) const
+{
+      fd << "-(";
+      write_to_stream_operand1(fd);
+      fd << ")";
+}
+
 void ExpCast::write_to_stream(ostream&fd) const
 {
       // Type casting is introduced only for a few specific cases in
diff --git a/vhdlpp/parse.y b/vhdlpp/parse.y
index 82ccde7e3..6b4c13e5d 100644
--- a/vhdlpp/parse.y
+++ b/vhdlpp/parse.y
@@ -2484,11 +2484,6 @@ shift_expression
       }
   ;
 
-sign
-  : '+'
-  | '-'
-  ;
-
 signal_declaration_assign_opt
   : VASSIGN expression { $$ = $2; }
   |                    { $$ = 0;  }
@@ -2514,10 +2509,10 @@ signal_declaration_assign_opt
  * list fixes up the associations.
  */
 simple_expression
-  : sign simple_expression_2
-      { sorrymsg(@1, "Unary expression +- not supported.\n");
-	$$ = $2;
-      }
+  : '-' simple_expression_2
+      { $$ = new ExpUMinus($2); }
+  | '+' simple_expression_2
+      { $$ = $2; }
   | simple_expression_2
       { $$ = $1; }
   ;