diff --git a/conf/airframes/ENAC/fixed-wing/funjet2.xml b/conf/airframes/ENAC/fixed-wing/funjet2.xml
index d4a7ba1292..0d224a5e6c 100644
--- a/conf/airframes/ENAC/fixed-wing/funjet2.xml
+++ b/conf/airframes/ENAC/fixed-wing/funjet2.xml
@@ -29,18 +29,14 @@
   </modules>
 
   <firmware name="fixedwing">
-    <target name="sim" board="pc">
-      <define name="AGR_CLIMB"/>
-      <define name="ALT_KALMAN"/>
-      <define name="LOITER_TRIM"/>
-      <define name="USE_I2C0"/>
-    </target>
+    <define name="USE_I2C0"/>
+    <define name="AGR_CLIMB"/>
+    <define name="ALT_KALMAN"/>
+    <define name="LOITER_TRIM"/>
+
+    <target name="sim" board="pc"/>
     <target name="ap" board="tiny_2.11">
       <param name="FLASH_MODE" value="IAP"/>
-      <define name="AGR_CLIMB"/>
-      <define name="ALT_KALMAN"/>
-      <define name="LOITER_TRIM"/>
-      <define name="USE_I2C0"/>
     </target>
 
     <subsystem name="radio_control" type="ppm"/>
diff --git a/conf/airframes/airframe.dtd b/conf/airframes/airframe.dtd
index 4feed28b55..ca0def88fe 100644
--- a/conf/airframes/airframe.dtd
+++ b/conf/airframes/airframe.dtd
@@ -25,7 +25,7 @@
 <!ELEMENT load (param|flag|define)*>
 <!ELEMENT param EMPTY>
 <!ELEMENT flag EMPTY>
-<!ELEMENT firmware (target|subsystem)*>
+<!ELEMENT firmware (target|subsystem|define)*>
 <!ELEMENT target (param|define)*>
 <!ELEMENT subsystem (param)*>
 
diff --git a/sw/tools/gen_aircraft.ml b/sw/tools/gen_aircraft.ml
index fec4d0d7b3..ca80d8b40f 100644
--- a/sw/tools/gen_aircraft.ml
+++ b/sw/tools/gen_aircraft.ml
@@ -298,6 +298,10 @@ let parse_targets = fun makefile_ac tag target ->
 	  List.iter (parse_subsystems makefile_ac tag) (Xml.children tag );    (** dump firware subsystems **)
 		  fprintf makefile_ac "endif\n\n";
 		with _ -> () end;
+  | "define" ->
+      let name = ExtXml.attrib target "name"
+      and value = try "="^(Xml.attrib target "value") with _ -> "" in
+      fprintf makefile_ac "$(TARGET).CFLAGS += -D%s%s\n" name value;
    | _ -> ()