diff --git a/cpu/native/Makefile b/cpu/native/Makefile
index 343092dfab..1891eebc41 100644
--- a/cpu/native/Makefile
+++ b/cpu/native/Makefile
@@ -3,6 +3,10 @@ MODULE = cpu
 DIRS += periph
 DIRS += vfs
 
+ifeq ($(shell uname -s),Darwin)
+  CFLAGS += -D_XOPEN_SOURCE=600 -D_DARWIN_C_SOURCE
+endif
+
 ifneq (,$(filter netdev_tap,$(USEMODULE)))
   DIRS += netdev_tap
 endif
diff --git a/cpu/native/Makefile.include b/cpu/native/Makefile.include
index 58c603eff5..b7a8d56bb8 100644
--- a/cpu/native/Makefile.include
+++ b/cpu/native/Makefile.include
@@ -7,7 +7,3 @@ endif
 
 USEMODULE += periph
 USEMODULE += periph_uart
-
-ifeq ($(shell uname -s),Darwin)
-export CFLAGS += -D_XOPEN_SOURCE=600 -D_DARWIN_C_SOURCE
-endif