diff --git a/include/uv/win.h b/include/uv/win.h
index a88bf29e9..7b4ebd4b7 100644
--- a/include/uv/win.h
+++ b/include/uv/win.h
@@ -279,7 +279,7 @@ typedef struct {
   DWORD tls_index;
 } uv_key_t;
 
-#define UV_ONCE_INIT { 0, NULL }
+#define UV_ONCE_INIT { 0, { NULL } }
 
 typedef struct uv_once_s {
   unsigned char unused;
diff --git a/src/win/udp.c b/src/win/udp.c
index f8aa2435c..33b4acc2b 100644
--- a/src/win/udp.c
+++ b/src/win/udp.c
@@ -1158,7 +1158,7 @@ int uv__udp_try_send2(uv_udp_t* handle,
   for (i = 0; i < (int) count; i++) {
     r = uv_udp_try_send(handle, bufs[i], nbufs[i], addrs[i]);
     if (r < 0)
-      return i > 0 ? i : r;  /* Error if first packet, else send count. */
+      return i > 0 ? i : (int) r;  /* Error if first packet, else send count. */
   }
 
   return i;
diff --git a/src/win/util.c b/src/win/util.c
index 9e3daac80..9fb5694c9 100644
--- a/src/win/util.c
+++ b/src/win/util.c
@@ -521,7 +521,7 @@ unsigned int uv_available_parallelism(void) {
    */
   count = 0;
   if (GetProcessAffinityMask(GetCurrentProcess(), &procmask, &sysmask))
-    for (i = 0; i < 8 * sizeof(procmask); i++)
+    for (i = 0; i < 8u * sizeof(procmask); i++)
       count += 1 & (procmask >> i);
 
   if (count > 0)