diff --git a/config.mk.orig b/config.mk
index d8d0129..1e99c67 100644
--- a/config.mk.orig
+++ b/config.mk
@@ -31,13 +31,13 @@ LIBS = -L$(X11LIB) -lX11 $(XINERAMALIBS) $(FREETYPELIBS)
 # flags
 # >>>>>>>>>>>>>>>>>>>> json
 # ==================== json
-CPPFLAGS = -D_DEFAULT_SOURCE -D_BSD_SOURCE -D_XOPEN_SOURCE=700 -D_POSIX_C_SOURCE=200809L -DVERSION=\"$(VERSION)\" $(XINERAMAFLAGS)
-CFLAGS   = -std=c99 -pedantic -Wall -Os $(INCS) $(CPPFLAGS)
+CPPFLAGS += -D_DEFAULT_SOURCE -D_BSD_SOURCE -D_XOPEN_SOURCE=700 -D_POSIX_C_SOURCE=200809L -DVERSION=\"$(VERSION)\" $(XINERAMAFLAGS)
+CFLAGS   += -std=c99 -pedantic -Wall -Os $(INCS) $(CPPFLAGS)
 # <<<<<<<<<<<<<<<<<<<< json
-LDFLAGS  = $(LIBS)
+LDFLAGS  += $(LIBS)
 
 # compiler and linker
-CC = cc
+CC ?= cc
 
 # >>>>>>>>>>>>>>>>>>>> json
 # ==================== json