diff --git a/conf/Makefile.avr b/conf/Makefile.avr
index d41e912025..7f38e698cd 100644
--- a/conf/Makefile.avr
+++ b/conf/Makefile.avr
@@ -28,7 +28,7 @@
 #
 
 ATMELBIN = /usr/bin
-ATMEL_INCLUDES = -I/usr/avr/include
+ATMEL_INCLUDES = -I /usr/avr/include
 ATMEL_LIBPATH = -B /usr/avr/lib/avr4 -B /usr/avr/lib/avr5
 PROG_PORT = /dev/parport0
 
diff --git a/conf/Makefile.sim b/conf/Makefile.sim
index 3d14d0909d..8097438bdf 100644
--- a/conf/Makefile.sim
+++ b/conf/Makefile.sim
@@ -35,7 +35,7 @@ CC = g++
 endif
 OCAMLC = ocamlc
 SIMDIR = $(PAPARAZZI_SRC)/sw/simulator
-CAMLINCLUDES = $(shell ocamlfind query -r -i-format lablgtk2) -I$(PAPARAZZI_SRC)/sw/lib/ocaml -I$(SIMDIR) $(shell ocamlfind query -r -i-format xml-light)
+CAMLINCLUDES = $(shell ocamlfind query -r -i-format lablgtk2) -I $(PAPARAZZI_SRC)/sw/lib/ocaml -I $(SIMDIR) $(shell ocamlfind query -r -i-format xml-light)
 SIMSITLML = $(OBJDIR)/simsitl.ml
 MYGTKINITCMO = myGtkInit.cmo
 SITLCMA = $(SIMDIR)/sitl.cma
@@ -48,7 +48,7 @@ Q=@
 #
 
 ifneq ($(SIM_TYPE),JSBSIM)
-INCLUDES += -I`ocamlc -where`
+INCLUDES += -I `ocamlc -where`
 endif
 
 CFLAGS  = -W -Wall