diff --git a/conf/boards/beagle_bone_black.makefile b/conf/boards/beagle_bone_black.makefile
index fa9571f335..1ca70dd37b 100644
--- a/conf/boards/beagle_bone_black.makefile
+++ b/conf/boards/beagle_bone_black.makefile
@@ -30,6 +30,7 @@ MODEM_BAUD ?= B57600
 
 # handle linux signals by hand (CTRL-C twice to stop)
 #$(TARGET).CFLAGS += -DUSE_LINUX_SIGNAL
+$(TARGET).CFLAGS += -D_GNU_SOURCE
 
 # -----------------------------------------------------------------------