diff --git a/configure.ac b/configure.ac
index f96ccf2..238b9b2 100644
--- a/configure.ac
+++ b/configure.ac
@@ -21,20 +21,16 @@ AC_ARG_ENABLE(ncurses,
 
 USE_SLANG=false
 USE_NCURSES=false
-if test "${enable_ncurses}" = "yes"
-then
+if test "${enable_ncurses}" = "yes"; then
   AC_CHECK_HEADER(ncurses.h,:,AC_MSG_ERROR([cannot find ncurses headers]))
   AC_CHECK_LIB(ncurses,initscr,:,AC_MSG_ERROR([cannot find ncurses library]))
+  AC_DEFINE(USE_NCURSES, 1, Define if the backend driver is ncurses)
   USE_NCURSES=:
-else
-  if test "${enable_slang}" != "no"
-  then
-    AC_CHECK_HEADER(slang.h,:,AC_MSG_ERROR([cannot find slang headers]))
-    AC_CHECK_LIB(slang,SLkp_init,:,AC_MSG_ERROR([cannot find slang library]))
-    USE_SLANG=:
-  else
-    :
-  fi
+elif test "${enable_slang}" != "no"; then
+  AC_CHECK_HEADER(slang.h,:,AC_MSG_ERROR([cannot find slang headers]))
+  AC_CHECK_LIB(slang,SLkp_init,:,AC_MSG_ERROR([cannot find slang library]))
+  AC_DEFINE(USE_SLANG, 1, Define if the backend driver is slang)
+  USE_SLANG=:
 fi
 
 AM_CONDITIONAL(USE_SLANG, ${USE_SLANG})
diff --git a/libee/Makefile.am b/libee/Makefile.am
index 2bf265e..36bbe51 100644
--- a/libee/Makefile.am
+++ b/libee/Makefile.am
@@ -7,13 +7,6 @@ AM_CFLAGS = -g -O2 -fno-strength-reduce -fomit-frame-pointer
 # Code qui fait des warnings == code de porc == deux baffes dans ta gueule
 AM_CFLAGS += -Wall -Wpointer-arith -Wcast-align -Wcast-qual -Wstrict-prototypes -Wshadow -Waggregate-return -Wmissing-prototypes -Wnested-externs
 
-if USE_SLANG
-CPPFLAGS_slang = -DUSE_SLANG
-endif
-if USE_NCURSES
-CPPFLAGS_ncurses = -DUSE_NCURSES
-endif
-
 lib_LIBRARIES = libee.a
 libee_a_SOURCES = \
 	ee.c \
@@ -24,5 +17,4 @@ libee_a_SOURCES = \
 	circle.c \
 	triangle.c \
 	$(NULL)
-libee_a_CPPFLAGS = $(CPPFLAGS_slang) $(CPPFLAGS_ncurses)
 
diff --git a/src/Makefile.am b/src/Makefile.am
index 0d05759..725ad26 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -8,11 +8,9 @@ AM_CFLAGS = -g -O2 -fno-strength-reduce -fomit-frame-pointer
 AM_CFLAGS += -Wall -Wpointer-arith -Wcast-align -Wcast-qual -Wstrict-prototypes -Wshadow -Waggregate-return -Wmissing-prototypes -Wnested-externs
 
 if USE_SLANG
-CPPFLAGS_slang = -DUSE_SLANG
 LDFLAGS_slang = -lslang
 endif
 if USE_NCURSES
-CPPFLAGS_ncurses = -DUSE_NCURSES
 LDFLAGS_ncurses = -lncurses
 endif
 
@@ -34,6 +32,6 @@ ttyvaders_SOURCES = \
 	weapons.c \
 	$(NULL)
 
-ttyvaders_CPPFLAGS = -I../libee $(CPPFLAGS_slang) $(CPPFLAGS_ncurses)
+ttyvaders_CPPFLAGS = -I../libee
 ttyvaders_LDADD = ../libee/libee.a $(LDFLAGS_slang) $(LDFLAGS_ncurses)
 
diff --git a/test/Makefile.am b/test/Makefile.am
index 665913f..bd65ff8 100644
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -8,17 +8,15 @@ AM_CFLAGS = -g -O2 -fno-strength-reduce -fomit-frame-pointer
 AM_CFLAGS += -Wall -Wpointer-arith -Wcast-align -Wcast-qual -Wstrict-prototypes -Wshadow -Waggregate-return -Wmissing-prototypes -Wnested-externs
 
 if USE_SLANG
-CPPFLAGS_slang = -DUSE_SLANG
 LDFLAGS_slang = -lslang
 endif
 if USE_NCURSES
-CPPFLAGS_ncurses = -DUSE_NCURSES
 LDFLAGS_ncurses = -lncurses
 endif
 
 bin_PROGRAMS = demo
 demo_SOURCES = demo.c
 
-demo_CPPFLAGS = -I../libee $(CPPFLAGS_slang) $(CPPFLAGS_ncurses)
+demo_CPPFLAGS = -I../libee
 demo_LDADD = ../libee/libee.a $(LDFLAGS_slang) $(LDFLAGS_ncurses) -lm