1 files changed, 1 insertions, 1 deletions

diff --git a/Makefile b/Makefile
index 3fdfcd2..8c7b6eb 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,4 @@
-CFLAGS += -std=c99 -D_XOPEN_SOURCE=500 -Wall -Wextra
+CFLAGS += -std=c99 -D_XOPEN_SOURCE=500 -D_POSIX_C_SOURCE=200809L -Wall -Wextra
 
 all: simulator