diff --git a/conf/airframes/AirborneCodeReorg/TinyFw.xml b/conf/airframes/AirborneCodeReorg/TinyFw.xml
index 7a21b47df9..d3b11146be 100644
--- a/conf/airframes/AirborneCodeReorg/TinyFw.xml
+++ b/conf/airframes/AirborneCodeReorg/TinyFw.xml
@@ -165,6 +165,7 @@
       <param name="FLASH_MODE" 		value="IAP" />
       <define name="AGR_CLIMB" />
       <define name="ALT_KALMAN" />
+      <define name="GENERIC" value="1" />
     </target>
     <target name="sim" 			board="pc" />
 
diff --git a/sw/tools/gen_aircraft.ml b/sw/tools/gen_aircraft.ml
index 21f35ec38c..a68aa507c0 100644
--- a/sw/tools/gen_aircraft.ml
+++ b/sw/tools/gen_aircraft.ml
@@ -239,9 +239,16 @@ let parse_targets = fun makefile_ac tag target ->
 **)          fprintf makefile_ac "include $(PAPARAZZI_SRC)/conf/autopilot/%s.makefile\n" (Xml.attrib tag "name");
   	  let print_if_subsystem = (fun d ->
             if ExtXml.tag_is d "define" then begin
-              fprintf makefile_ac "%s.CFLAGS += -D%s\n"
+              let has_def_value = ref false in
+              begin try
+                has_def_value := not (String.compare (Xml.attrib d "value") "" = 0)
+              with _ -> () end;
+              fprintf makefile_ac "%s.CFLAGS += -D%s"
                 (Xml.attrib target "name")
-                (Xml.attrib d "name")
+                (Xml.attrib d "name");
+              if !has_def_value then
+                fprintf makefile_ac "=%s" (Xml.attrib d "value");
+              fprintf makefile_ac "\n"
             end) in
 	  List.iter print_if_subsystem (Xml.children target);
 	  List.iter (parse_subsystems makefile_ac tag) (Xml.children target ); (** dump target  subsystems **)