diff --git a/lib/searpc-named-pipe-transport.c b/lib/searpc-named-pipe-transport.c
index f186adb..8297286 100644
--- a/lib/searpc-named-pipe-transport.c
+++ b/lib/searpc-named-pipe-transport.c
@@ -221,7 +221,7 @@ static void* named_pipe_client_handler(void *arg)
 
     while (1) {
         len = 0;
-        if (pipe_read_n(connfd, &len, sizeof(size_t)) < 0) {
+        if (pipe_read_n(connfd, &len, sizeof(uint32_t)) < 0) {
             g_warning("failed to read rpc request size: %s", strerror(errno));
             break;
         }
@@ -252,7 +252,7 @@ static void* named_pipe_client_handler(void *arg)
         g_free (service);
         g_free (body);
 
-        if (pipe_write_n(connfd, &ret_len, sizeof(size_t)) < 0) {
+        if (pipe_write_n(connfd, &ret_len, sizeof(uint32_t)) < 0) {
             g_warning("failed to send rpc response(%s): %s", ret_str, strerror(errno));
             g_free (ret_str);
             break;
@@ -346,8 +346,8 @@ char *searpc_named_pipe_send(void *arg, const gchar *fcall_str,
     char *json_str = request_to_json(data->service, fcall_str, fcall_len);
     size_t json_len = strlen(json_str);
 
-    size_t len = json_len;
-    if (pipe_write_n(client->pipe_fd, &len, sizeof(size_t)) < 0) {
+    uint32_t len = json_len;
+    if (pipe_write_n(client->pipe_fd, &len, sizeof(uint32_t)) < 0) {
         g_warning("failed to send rpc call: %s", strerror(errno));
         free (json_str);
         return NULL;
@@ -361,7 +361,7 @@ char *searpc_named_pipe_send(void *arg, const gchar *fcall_str,
 
     free (json_str);
 
-    if (pipe_read_n(client->pipe_fd, &len, sizeof(size_t)) < 0) {
+    if (pipe_read_n(client->pipe_fd, &len, sizeof(uint32_t)) < 0) {
         g_warning("failed to read rpc response: %s", strerror(errno));
         return NULL;
     }