diff --git a/Makefile b/Makefile
index 05516e073ca375d948bc86aa9f0d088c95af6b2c..e1f9761eefc98d14b76d92de64a28373ccc31633 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,4 @@
-CFLAGS += -std=c11 -D_POSIX_SOURCE -Wall -Wconversion -fPIC
+CFLAGS += -std=c11 -D_POSIX_C_SOURCE=201112 -Wall -Wconversion -fPIC
 
 goatherd: goatherd.go
 	go build goatherd.go