diff --git a/vhdlpp/architec_emit.cc b/vhdlpp/architec_emit.cc
index cf18cdd84..d0d3fb1ff 100644
--- a/vhdlpp/architec_emit.cc
+++ b/vhdlpp/architec_emit.cc
@@ -150,6 +150,22 @@ int ComponentInstantiation::emit(ostream&out, Entity*ent, Architecture*arc)
 
       arc->set_cur_component(this);
 
+      if(ComponentBase*comp = arc->find_component(cname_)) {
+        const std::vector<InterfacePort*>& generics = comp->get_generics();
+
+      if(generics.size() != generic_map_.size())
+	    // Display an error for generics that do not have neither
+	    // default nor component specific value defined
+	    for(vector<InterfacePort*>::const_iterator it = generics.begin();
+			it != generics.end(); ++it) {
+		if(!(*it)->expr && generic_map_.count((*it)->name) == 0) {
+		    cerr << get_fileline() << ": generic " << (*it)->name <<
+			"value is not defined" << endl;
+		    ++errors;
+		}
+	    }
+      }
+
       out << cname_;
       if (! generic_map_.empty()) {
 	    out << " #(";
diff --git a/vhdlpp/entity.h b/vhdlpp/entity.h
index 8c41e52ab..5e183d1a5 100644
--- a/vhdlpp/entity.h
+++ b/vhdlpp/entity.h
@@ -63,6 +63,7 @@ class ComponentBase : public LineInfo {
 
       const InterfacePort* find_port(perm_string by_name) const;
       const InterfacePort* find_generic(perm_string by_name) const;
+      const std::vector<InterfacePort*>& get_generics() const { return parms_; }
 
 	// Declare the ports for the entity. The parser calls this
 	// method with a list of interface elements that were parsed