-CPPFLAGS = -DVERSION=\"${VERSION}\" -DWEBEXTDIR=\"${LIBPREFIX}\" -D_DEFAULT_SOURCE
-SURF_CFLAGS = $(INCS) $(CPPFLAGS) $(CFLAGS)
-SURF_LDFLAGS = $(LIBS) $(LDFLAGS)
+CPPFLAGS = -DVERSION=\"$(VERSION)\" -DWEBEXTDIR=\"$(LIBPREFIX)\" \
+ -D_DEFAULT_SOURCE -DGCR_API_SUBJECT_TO_CHANGE
+SURFCFLAGS = $(INCS) $(CPPFLAGS) $(CFLAGS)
+SURFLDFLAGS = $(LIBS) $(LDFLAGS)
+LIBCPPFLAGS = -DWEBEXTDIR=\"$(LIBPREFIX)\"
+LIBCFLAGS = $(WEBEXTINC) $(LIBCPPFLAGS) $(CFLAGS)
+LIBLDFLAGS = $(WEBEXTLIB) $(LDFLAGS)