diff --git a/Makefile b/Makefile
index 517959c..36bc50f 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,6 @@
 .POSIX:
 .SUFFIXES: .c .o
 
-CC = cc # c99 (default value) does not allow POSIX extensions.
 PROJECT = slcl
 O = -Og
 CDEFS = -D_FILE_OFFSET_BITS=64 # Required for large file support on 32-bit.
diff --git a/handler.c b/handler.c
index 22699f5..73ac9ab 100644
--- a/handler.c
+++ b/handler.c
@@ -1,3 +1,5 @@
+#define _POSIX_C_SOURCE 200809L
+
 #include "handler.h"
 #include "http.h"
 #include "server.h"
diff --git a/html.c b/html.c
index cad966b..41ce387 100644
--- a/html.c
+++ b/html.c
@@ -1,3 +1,5 @@
+#define _POSIX_C_SOURCE 200809L
+
 #include "html.h"
 #include <dynstr.h>
 #include <errno.h>
diff --git a/http.c b/http.c
index b3b65d4..9126d7f 100644
--- a/http.c
+++ b/http.c
@@ -1,3 +1,5 @@
+#define _POSIX_C_SOURCE 200809L
+
 #include "http.h"
 #include <dynstr.h>
 #include <sys/types.h>
diff --git a/main.c b/main.c
index 89edae3..8e070ba 100644
--- a/main.c
+++ b/main.c
@@ -1,3 +1,5 @@
+#define _POSIX_C_SOURCE 200809L
+
 #include "auth.h"
 #include "cftw.h"
 #include "handler.h"
diff --git a/page.c b/page.c
index 5cbb0a7..9776349 100644
--- a/page.c
+++ b/page.c
@@ -1,3 +1,5 @@
+#define _POSIX_C_SOURCE 200809L
+
 #include "page.h"
 #include "http.h"
 #include "html.h"
diff --git a/server.c b/server.c
index 40be54e..f740384 100644
--- a/server.c
+++ b/server.c
@@ -1,3 +1,5 @@
+#define _POSIX_C_SOURCE 200809L
+
 #include "server.h"
 #include <fcntl.h>
 #include <sys/select.h>