diff --git a/test/benchmark-ping-pongs.c b/test/benchmark-ping-pongs.c
index 43a13216..368380ea 100644
--- a/test/benchmark-ping-pongs.c
+++ b/test/benchmark-ping-pongs.c
@@ -46,13 +46,13 @@ typedef struct buf_s {
 
 static char PING[] = "PING\n";
 
-buf_t* buf_freelist = NULL;
+static buf_t* buf_freelist = NULL;
 
 static int completed_pingers = 0;
 static int64_t start_time;
 
 
-oio_buf buf_alloc(oio_handle* handle, size_t size) {
+static oio_buf buf_alloc(oio_handle* handle, size_t size) {
   buf_t* ab;
 
   ab = buf_freelist;
@@ -70,7 +70,7 @@ oio_buf buf_alloc(oio_handle* handle, size_t size) {
 }
 
 
-void buf_free(oio_buf oio_buf) {
+static void buf_free(oio_buf oio_buf) {
   buf_t* ab = (buf_t*) (oio_buf.base - sizeof *ab);
 
   ab->next = buf_freelist;
@@ -78,7 +78,7 @@ void buf_free(oio_buf oio_buf) {
 }
 
 
-void pinger_close_cb(oio_handle* handle, int status) {
+static void pinger_close_cb(oio_handle* handle, int status) {
   pinger_t* pinger;
 
   ASSERT(status == 0);
@@ -92,7 +92,7 @@ void pinger_close_cb(oio_handle* handle, int status) {
 }
 
 
-void pinger_write_cb(oio_req *req, int status) {
+static void pinger_write_cb(oio_req *req, int status) {
   ASSERT(status == 0);
 
   free(req);
@@ -157,7 +157,7 @@ static void pinger_read_cb(oio_handle* handle, int nread, oio_buf buf) {
 }
 
 
-void pinger_connect_cb(oio_req *req, int status) {
+static void pinger_connect_cb(oio_req *req, int status) {
   pinger_t *pinger = (pinger_t*)req->handle->data;
 
   ASSERT(status == 0);
@@ -170,7 +170,7 @@ void pinger_connect_cb(oio_req *req, int status) {
 }
 
 
-void pinger_new() {
+static void pinger_new() {
   int r;
   struct sockaddr_in client_addr = oio_ip4_addr("0.0.0.0", 0);
   struct sockaddr_in server_addr = oio_ip4_addr("127.0.0.1", TEST_PORT);
diff --git a/test/echo-server.c b/test/echo-server.c
index 8ecbd61a..ee3c925c 100644
--- a/test/echo-server.c
+++ b/test/echo-server.c
@@ -31,16 +31,16 @@ typedef struct {
 } write_req_t;
 
 
-oio_handle server;
+static oio_handle server;
 
 
-void after_write(oio_req* req, int status);
-void after_read(oio_handle* handle, int nread, oio_buf buf);
-void on_close(oio_handle* peer, int status);
-void on_accept(oio_handle* handle);
+static void after_write(oio_req* req, int status);
+static void after_read(oio_handle* handle, int nread, oio_buf buf);
+static void on_close(oio_handle* peer, int status);
+static void on_accept(oio_handle* handle);
 
 
-void after_write(oio_req* req, int status) {
+static void after_write(oio_req* req, int status) {
   write_req_t* wr;
 
   if (status) {
@@ -57,12 +57,12 @@ void after_write(oio_req* req, int status) {
 }
 
 
-void after_shutdown(oio_req* req, int status) {
+static void after_shutdown(oio_req* req, int status) {
   free(req);
 }
 
 
-void after_read(oio_handle* handle, int nread, oio_buf buf) {
+static void after_read(oio_handle* handle, int nread, oio_buf buf) {
   write_req_t *wr;
   oio_req* req;
 
@@ -98,14 +98,14 @@ void after_read(oio_handle* handle, int nread, oio_buf buf) {
 }
 
 
-void on_close(oio_handle* peer, int status) {
+static void on_close(oio_handle* peer, int status) {
   if (status != 0) {
     fprintf(stdout, "Socket error\n");
   }
 }
 
 
-void on_accept(oio_handle* server) {
+static void on_accept(oio_handle* server) {
   oio_handle* handle = (oio_handle*) malloc(sizeof *handle);
 
   if (oio_accept(server, handle, on_close, NULL)) {
@@ -116,13 +116,13 @@ void on_accept(oio_handle* server) {
 }
 
 
-void on_server_close(oio_handle* handle, int status) {
+static void on_server_close(oio_handle* handle, int status) {
   ASSERT(handle == &server);
   ASSERT(status == 0);
 }
 
 
-int echo_start(int port) {
+static int echo_start(int port) {
   struct sockaddr_in addr = oio_ip4_addr("0.0.0.0", port);
   int r;
 
@@ -151,12 +151,12 @@ int echo_start(int port) {
 }
 
 
-int echo_stop() {
+static int echo_stop() {
   return oio_close(&server);
 }
 
 
-oio_buf echo_alloc(oio_handle* handle, size_t suggested_size) {
+static oio_buf echo_alloc(oio_handle* handle, size_t suggested_size) {
   oio_buf buf;
   buf.base = (char*) malloc(suggested_size);
   buf.len = suggested_size;
diff --git a/test/test-callback-stack.c b/test/test-callback-stack.c
index 33793f54..edf42d9d 100644
--- a/test/test-callback-stack.c
+++ b/test/test-callback-stack.c
@@ -28,21 +28,21 @@
 #include "task.h"
 
 
-const char MESSAGE[] = "Failure is for the weak. Everyone dies alone.";
+static const char MESSAGE[] = "Failure is for the weak. Everyone dies alone.";
 
-oio_handle client;
-oio_req connect_req, write_req, timeout_req, shutdown_req;
+static oio_handle client;
+static oio_req connect_req, write_req, timeout_req, shutdown_req;
 
-int nested = 0;
-int close_cb_called = 0;
-int connect_cb_called = 0;
-int write_cb_called = 0;
-int timeout_cb_called = 0;
-int bytes_received = 0;
-int shutdown_cb_called = 0;
+static int nested = 0;
+static int close_cb_called = 0;
+static int connect_cb_called = 0;
+static int write_cb_called = 0;
+static int timeout_cb_called = 0;
+static int bytes_received = 0;
+static int shutdown_cb_called = 0;
 
 
-void close_cb(oio_handle* handle, int status) {
+static void close_cb(oio_handle* handle, int status) {
   ASSERT(status == 0);
   ASSERT(nested == 0 && "close_cb must be called from a fresh stack");
 
@@ -50,7 +50,7 @@ void close_cb(oio_handle* handle, int status) {
 }
 
 
-void shutdown_cb(oio_req* req, int status) {
+static void shutdown_cb(oio_req* req, int status) {
   ASSERT(status == 0);
   ASSERT(nested == 0 && "shutdown_cb must be called from a fresh stack");
 
@@ -58,7 +58,7 @@ void shutdown_cb(oio_req* req, int status) {
 }
 
 
-void read_cb(oio_handle* handle, int nread, oio_buf buf) {
+static void read_cb(oio_handle* handle, int nread, oio_buf buf) {
   ASSERT(nested == 0 && "read_cb must be called from a fresh stack");
 
   printf("Read. nread == %d\n", nread);
@@ -100,7 +100,7 @@ void read_cb(oio_handle* handle, int nread, oio_buf buf) {
 }
 
 
-void timeout_cb(oio_req* req, int64_t skew, int status) {
+static void timeout_cb(oio_req* req, int64_t skew, int status) {
   ASSERT(status == 0);
   ASSERT(nested == 0 && "timeout_cb must be called from a fresh stack");
 
@@ -116,7 +116,7 @@ void timeout_cb(oio_req* req, int64_t skew, int status) {
 }
 
 
-void write_cb(oio_req* req, int status) {
+static void write_cb(oio_req* req, int status) {
   ASSERT(status == 0);
   ASSERT(nested == 0 && "write_cb must be called from a fresh stack");
 
@@ -137,7 +137,7 @@ void write_cb(oio_req* req, int status) {
 }
 
 
-void connect_cb(oio_req* req, int status) {
+static void connect_cb(oio_req* req, int status) {
   oio_buf buf;
 
   puts("Connected. Write some data to echo server...");
diff --git a/test/test-ping-pong.c b/test/test-ping-pong.c
index 21ebadf5..afba7579 100644
--- a/test/test-ping-pong.c
+++ b/test/test-ping-pong.c
@@ -48,7 +48,7 @@ typedef struct {
 void pinger_try_read(pinger_t* pinger);
 
 
-void pinger_on_close(oio_handle* handle, int status) {
+static void pinger_on_close(oio_handle* handle, int status) {
   pinger_t* pinger = (pinger_t*)handle->data;
 
   ASSERT(status == 0);
@@ -60,7 +60,7 @@ void pinger_on_close(oio_handle* handle, int status) {
 }
 
 
-void pinger_after_write(oio_req *req, int status) {
+static void pinger_after_write(oio_req *req, int status) {
   ASSERT(status == 0);
 
   free(req);
@@ -123,7 +123,7 @@ static void pinger_read_cb(oio_handle* handle, int nread, oio_buf buf) {
 }
 
 
-void pinger_on_connect(oio_req *req, int status) {
+static void pinger_on_connect(oio_req *req, int status) {
   pinger_t *pinger = (pinger_t*)req->handle->data;
 
   ASSERT(status == 0);
@@ -134,7 +134,7 @@ void pinger_on_connect(oio_req *req, int status) {
 }
 
 
-void pinger_new() {
+static void pinger_new() {
   int r;
   struct sockaddr_in server_addr = oio_ip4_addr("127.0.0.1", TEST_PORT);
   pinger_t *pinger;