diff --git a/src/conio/Common.make b/src/conio/Common.make
index 9ce1653e2f728f2c044ac4f62b8becca80953a21..f570b320a202cfb7ccd6c416cecb89da6497ca63 100644
--- a/src/conio/Common.make
+++ b/src/conio/Common.make
@@ -1,5 +1,5 @@
 CIOLIB-MT	=	$(CIOLIB_SRC)$(DIRSEP)$(LIBODIR)$(DIRSEP)$(LIBPREFIX)ciolib_mt$(LIBFILE)
 
-CIOLIB-MT_CFLAGS	=	-I$(CIOLIB_SRC)
+CIOLIB-MT_CFLAGS	=	-I$(CIOLIB_SRC) -DCIOLIB_APP
 CIOLIB-MT_LDFLAGS	=	-L$(CIOLIB_SRC)$(DIRSEP)$(LIBODIR)
 CIOLIB-MT_LIBS		=	$(UL_PRE)ciolib_mt$(UL_SUF)