diff --git a/3rdparty/libuv b/3rdparty/libuv
index 666aa2f068..49cb40c479 160000
--- a/3rdparty/libuv
+++ b/3rdparty/libuv
@@ -1 +1 @@
-Subproject commit 666aa2f0683dc8b80954c01e5799d476e4068350
+Subproject commit 49cb40c47902dd04c7787e6543e9e13368dc1840
diff --git a/build/Makefile.in b/build/Makefile.in
index 9e4f4d33a1..4ed56526de 100644
--- a/build/Makefile.in
+++ b/build/Makefile.in
@@ -344,7 +344,7 @@ UV_UNIX = 3rdparty/libuv/src/fs-poll@obj@ \
           3rdparty/libuv/src/unix/stream@obj@ \
           3rdparty/libuv/src/unix/tcp@obj@ \
           3rdparty/libuv/src/unix/thread@obj@ \
-          3rdparty/libuv/src/unix/threadpool@obj@ \
+          3rdparty/libuv/src/threadpool@obj@ \
           3rdparty/libuv/src/unix/timer@obj@ \
           3rdparty/libuv/src/unix/tty@obj@ \
           3rdparty/libuv/src/unix/udp@obj@
diff --git a/src/io/dirops.c b/src/io/dirops.c
index 862f1357f9..902864fd5e 100644
--- a/src/io/dirops.c
+++ b/src/io/dirops.c
@@ -150,14 +150,15 @@ void MVM_dir_rmdir(MVMThreadContext *tc, MVMString *path) {
 MVMString * MVM_dir_cwd(MVMThreadContext *tc) {
 #ifdef _WIN32
     char path[MAX_PATH];
-    const size_t max_path = MAX_PATH;
+    size_t max_path = MAX_PATH;
+    int r;
 #else
     char path[PATH_MAX];
-    const size_t max_path = PATH_MAX;
-#endif
+    size_t max_path = PATH_MAX;
     int r;
+#endif
 
-    if ((r = uv_cwd(path, max_path)) < 0) {
+    if ((r = uv_cwd(path, (size_t *)&max_path)) < 0) {
         MVM_exception_throw_adhoc(tc, "chdir failed: %s", uv_strerror(r));
     }
 
diff --git a/src/io/eventloop.c b/src/io/eventloop.c
index 8244daa538..e0bdc735d3 100644
--- a/src/io/eventloop.c
+++ b/src/io/eventloop.c
@@ -43,7 +43,7 @@ static MVMint64 cancel_work(MVMThreadContext *tc) {
 
 /* Sees if we have an event loop processing thread set up already, and
  * sets it up if not. */
-static void idle_handler(uv_idle_t *handle, int status) {
+static void idle_handler(uv_idle_t *handle) {
     MVMThreadContext *tc = (MVMThreadContext *)handle->data;
     GC_SYNC_POINT(tc);
     if (!setup_work(tc) && !cancel_work(tc))
diff --git a/src/io/syncfile.c b/src/io/syncfile.c
index 1719aea24c..7b06b2460b 100644
--- a/src/io/syncfile.c
+++ b/src/io/syncfile.c
@@ -91,10 +91,11 @@ static void set_separator(MVMThreadContext *tc, MVMOSHandle *h, MVMString *sep)
 
 /* Read a bunch of bytes into the current decode stream. */
 static MVMint32 read_to_buffer(MVMThreadContext *tc, MVMIOFileData *data, MVMint32 bytes) {
-    char *buf = MVM_malloc(bytes);
+    char *buf         = MVM_malloc(bytes);
+    uv_buf_t read_buf = uv_buf_init(buf, bytes);
     uv_fs_t req;
     MVMint32 read;
-    if ((read = uv_fs_read(tc->loop, &req, data->fd, buf, bytes, -1, NULL)) < 0) {
+    if ((read = uv_fs_read(tc->loop, &req, data->fd, &read_buf, 1, -1, NULL)) < 0) {
         MVM_free(buf);
         MVM_exception_throw_adhoc(tc, "Reading from filehandle failed: %s",
             uv_strerror(req.result));
@@ -211,7 +212,8 @@ static MVMint64 write_str(MVMThreadContext *tc, MVMOSHandle *h, MVMString *str,
     MVM_free(output);
 
     if (newline) {
-        if (uv_fs_write(tc->loop, &req, data->fd, "\n", 1, -1, NULL) < 0)
+        uv_buf_t nl = uv_buf_init("\n", 1);
+        if (uv_fs_write(tc->loop, &req, data->fd, &nl, 1, -1, NULL) < 0)
             MVM_exception_throw_adhoc(tc, "Failed to write newline to filehandle: %s", uv_strerror(req.result));
         bytes_written++;
     }
diff --git a/src/io/timers.c b/src/io/timers.c
index 3be7964206..e0ef559ee3 100644
--- a/src/io/timers.c
+++ b/src/io/timers.c
@@ -10,7 +10,7 @@ typedef struct {
 } TimerInfo;
 
 /* Timer callback; dispatches schedulee to the queue. */
-static void timer_cb(uv_timer_t *handle, int status) {
+static void timer_cb(uv_timer_t *handle) {
     TimerInfo        *ti = (TimerInfo *)handle->data;
     MVMThreadContext *tc = ti->tc;
     MVMAsyncTask     *t  = (MVMAsyncTask *)MVM_repr_at_pos_o(tc,