diff --git a/conf/firmwares/subsystems/fixedwing/fdm_jsbsim.makefile b/conf/firmwares/subsystems/fixedwing/fdm_jsbsim.makefile
index c7fe64940e..3d78316b4a 100644
--- a/conf/firmwares/subsystems/fixedwing/fdm_jsbsim.makefile
+++ b/conf/firmwares/subsystems/fixedwing/fdm_jsbsim.makefile
@@ -24,7 +24,7 @@ nps.srcs    += $(fbw_srcs) $(ap_srcs)
 nps.CFLAGS  += -DSITL -DUSE_NPS
 nps.CFLAGS  += $(shell pkg-config glib-2.0 --cflags)
 nps.LDFLAGS += $(shell pkg-config glib-2.0 --libs) -lm -lglibivy $(shell pcre-config --libs) -lgsl -lgslcblas
-nps.CFLAGS  += -I$(SRC_FIRMWARE) -I$(SRC_BOARD) -I$(PAPARAZZI_SRC)/sw/simulator/nps -I$(PAPARAZZI_HOME)/conf/simulator/nps
+nps.CFLAGS  += -I$(SRC_FIRMWARE) -I$(SRC_BOARD) -I$(PAPARAZZI_SRC)/sw/simulator -I$(PAPARAZZI_SRC)/sw/simulator/nps -I$(PAPARAZZI_HOME)/conf/simulator/nps
 nps.LDFLAGS += $(shell sdl-config --libs)
 
 # use the paparazzi-jsbsim package if it is installed, otherwise look for JSBsim under /opt/jsbsim
diff --git a/conf/firmwares/subsystems/rotorcraft/fdm_jsbsim.makefile b/conf/firmwares/subsystems/rotorcraft/fdm_jsbsim.makefile
index e80ce496d6..020dbcf369 100644
--- a/conf/firmwares/subsystems/rotorcraft/fdm_jsbsim.makefile
+++ b/conf/firmwares/subsystems/rotorcraft/fdm_jsbsim.makefile
@@ -20,7 +20,7 @@ nps.MAKEFILE = nps
 nps.CFLAGS  += -DSITL -DUSE_NPS
 nps.CFLAGS  += $(shell pkg-config glib-2.0 --cflags)
 nps.LDFLAGS += $(shell pkg-config glib-2.0 --libs) -lm -lglibivy $(shell pcre-config --libs) -lgsl -lgslcblas
-nps.CFLAGS  += -I$(SRC_FIRMWARE) -I$(SRC_BOARD) -I$(PAPARAZZI_SRC)/sw/simulator/nps -I$(PAPARAZZI_HOME)/conf/simulator/nps
+nps.CFLAGS  += -I$(SRC_FIRMWARE) -I$(SRC_BOARD) -I$(PAPARAZZI_SRC)/sw/simulator -I$(PAPARAZZI_SRC)/sw/simulator/nps -I$(PAPARAZZI_HOME)/conf/simulator/nps
 nps.LDFLAGS += $(shell sdl-config --libs)
 
 # use the paparazzi-jsbsim package if it is installed, otherwise look for JSBsim under /opt/jsbsim