1 files changed, 1 insertions, 1 deletions

diff --git a/Makefile b/Makefile
index 78828dc..d922d90 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@
 .POSIX:
 .SUFFIXES:
 
-CFLAGS = -O2 -Wall -Wextra -pedantic
+CFLAGS = -O2 -Wall -Wextra -pedantic -D_POSIX_C_SOURCE=199309L -D_XOPEN_SOURCE
 LDFLAGS = -static
 LDLIBS = -lm