diff --git a/examples/contiki/Makefile.contiki b/examples/contiki/Makefile.contiki
index 5189a729..9df292a2 100644
--- a/examples/contiki/Makefile.contiki
+++ b/examples/contiki/Makefile.contiki
@@ -23,7 +23,7 @@ endif
 
 all: server
 
-CFLAGS += -ffunction-sections
+CFLAGS += -Os -ffunction-sections
 LDFLAGS += -Wl,--gc-sections,--undefined=_reset_vector__,--undefined=InterruptVectors,--undefined=_copy_data_init__,--undefined=_clear_bss_init__,--undefined=_end_of_init__
 
 CFLAGS += #-DSHORT_ERROR_RESPONSE -DNDEBUG