diff --git a/Makefile b/Makefile
index e5363d6..75c721b 100644
--- a/Makefile
+++ b/Makefile
@@ -3,7 +3,7 @@ PREFIX ?= /usr/local
 
 LIBS = -lm -ljpeg -pthread -levent -levent_pthreads
 CC = gcc
-CFLAGS = -c -O3 -Wall -Wextra
+CFLAGS = -c -std=c99 -O3 -Wall -Wextra -D_GNU_SOURCE
 LDFLAGS =
 SOURCES = $(shell ls src/*.c)
 OBJECTS = $(SOURCES:.c=.o)
diff --git a/src/logging.h b/src/logging.h
index 4f9966b..a0e3710 100644
--- a/src/logging.h
+++ b/src/logging.h
@@ -24,12 +24,16 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <unistd.h>
 #include <errno.h>
 #include <time.h>
 #include <assert.h>
 
 #include <pthread.h>
 
+#include <sys/types.h>
+#include <sys/syscall.h>
+
 #include "tools.h"