diff --git a/vhdlpp/expression.h b/vhdlpp/expression.h
index 97ebf629d..094ffd36b 100644
--- a/vhdlpp/expression.h
+++ b/vhdlpp/expression.h
@@ -496,6 +496,7 @@ class ExpUNot : public ExpUnary {
       ExpUNot(Expression*op1);
       ~ExpUNot();
 
+      int elaborate_expr(Entity*ent, Architecture*arc, const VType*ltype);
       int emit(ostream&out, Entity*ent, Architecture*arc);
       void dump(ostream&out, int indent = 0) const;
 };
diff --git a/vhdlpp/expression_elaborate.cc b/vhdlpp/expression_elaborate.cc
index ba73f4765..5b43c0b5e 100644
--- a/vhdlpp/expression_elaborate.cc
+++ b/vhdlpp/expression_elaborate.cc
@@ -310,7 +310,7 @@ int ExpConditional::elaborate_expr(Entity*ent, Architecture*arc, const VType*lty
       return errors;
 }
 
-int ExpFunc::elaborate_expr(Entity*ent, Architecture*arc, const VType*ltype)
+int ExpFunc::elaborate_expr(Entity*ent, Architecture*arc, const VType*)
 {
       int errors = 0;
 
@@ -430,3 +430,10 @@ int ExpString::elaborate_expr(Entity*, Architecture*, const VType*ltype)
       set_type(ltype);
       return 0;
 }
+
+int ExpUNot::elaborate_expr(Entity*, Architecture*, const VType*ltype)
+{
+      ivl_assert(*this, ltype != 0);
+      set_type(ltype);
+      return 0;
+}