diff --git a/src/Makefile b/src/Makefile
index ec75052..2dd7f6a 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -32,7 +32,7 @@ endif
 endif
 
 CFLAGS ?= -O3
-CFLAGS += -std=gnu11
+CFLAGS += -std=gnu11 -D_GNU_SOURCE
 CFLAGS += -Wall -Wextra
 CFLAGS += -MMD -MP
 CFLAGS += -DRUNSTATEDIR="\"$(RUNSTATEDIR)\""
diff --git a/src/terminal.c b/src/terminal.c
index 862bb4a..e5b5edb 100644
--- a/src/terminal.c
+++ b/src/terminal.c
@@ -1,6 +1,5 @@
 /* Copyright (C) 2015-2017 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved. */
 
-#define _GNU_SOURCE
 #include <ctype.h>
 #include <stdarg.h>
 #include <stddef.h>