diff --git a/src/core/ddsi/include/ddsi/ddsi_ipaddr.h b/src/core/ddsi/include/ddsi/ddsi_ipaddr.h
index e0e575a..9a86d85 100644
--- a/src/core/ddsi/include/ddsi/ddsi_ipaddr.h
+++ b/src/core/ddsi/include/ddsi/ddsi_ipaddr.h
@@ -14,7 +14,7 @@
 
 #include "ddsi/ddsi_tran.h"
 
-enum ddsi_nearby_address_result ddsi_ipaddr_is_nearby_address (ddsi_tran_factory_t tran, const nn_locator_t *loc, const size_t ninterf, const struct nn_interface interf[]);
+enum ddsi_nearby_address_result ddsi_ipaddr_is_nearby_address (ddsi_tran_factory_t tran, const nn_locator_t *loc, size_t ninterf, const struct nn_interface interf[]);
 enum ddsi_locator_from_string_result ddsi_ipaddr_from_string (ddsi_tran_factory_t tran, nn_locator_t *loc, const char *str, int32_t kind);
 char *ddsi_ipaddr_to_string (ddsi_tran_factory_t tran, char *dst, size_t sizeof_dst, const nn_locator_t *loc, int with_port);
 void ddsi_ipaddr_to_loc (nn_locator_t *dst, const os_sockaddr_storage *src, int32_t kind);
diff --git a/src/core/ddsi/include/ddsi/ddsi_tran.h b/src/core/ddsi/include/ddsi/ddsi_tran.h
index 178e271..27af518 100644
--- a/src/core/ddsi/include/ddsi/ddsi_tran.h
+++ b/src/core/ddsi/include/ddsi/ddsi_tran.h
@@ -220,7 +220,7 @@ int ddsi_conn_rejoin_transferred_mcgroups (ddsi_tran_conn_t conn);
 
 int ddsi_is_mcaddr (const nn_locator_t *loc);
 int ddsi_is_ssm_mcaddr (const nn_locator_t *loc);
-enum ddsi_nearby_address_result ddsi_is_nearby_address (const nn_locator_t *loc, const size_t ninterf, const struct nn_interface interf[]);
+enum ddsi_nearby_address_result ddsi_is_nearby_address (const nn_locator_t *loc, size_t ninterf, const struct nn_interface interf[]);
 enum ddsi_locator_from_string_result ddsi_locator_from_string (nn_locator_t *loc, const char *str);
 
 /*  8 for transport/
diff --git a/src/core/ddsi/include/ddsi/sysdeps.h b/src/core/ddsi/include/ddsi/sysdeps.h
index f8a9c2b..3450322 100644
--- a/src/core/ddsi/include/ddsi/sysdeps.h
+++ b/src/core/ddsi/include/ddsi/sysdeps.h
@@ -134,9 +134,11 @@ extern "C" {
 
 #if SYSDEPS_HAVE_IOVEC
 typedef struct iovec ddsi_iovec_t;
+typedef size_t ddsi_iov_len_t;
 #elif defined _WIN32 && !defined WINCE
+typedef unsigned ddsi_iov_len_t;
 typedef struct ddsi_iovec {
-  unsigned iov_len;
+  ddsi_iov_len_t iov_len;
   void *iov_base;
 } ddsi_iovec_t;
 #define DDSI_IOVEC_MATCHES_WSABUF do { \
@@ -148,9 +150,10 @@ typedef struct ddsi_iovec {
     char len_size_matches[sizeof(((struct ddsi_iovec *)8)->iov_len) == sizeof(((WSABUF *)8)->len) ? 1 : -1]; \
   }; } while (0)
 #else
+typedef size_t ddsi_iov_len_t;
 typedef struct ddsi_iovec {
   void *iov_base;
-  size_t iov_len;
+  ddsi_iov_len_t iov_len;
 } ddsi_iovec_t;
 #endif
 
diff --git a/src/core/ddsi/src/ddsi_udp.c b/src/core/ddsi/src/ddsi_udp.c
index 586545d..da5c5e5 100644
--- a/src/core/ddsi/src/ddsi_udp.c
+++ b/src/core/ddsi/src/ddsi_udp.c
@@ -57,7 +57,7 @@ static ssize_t ddsi_udp_conn_read (ddsi_tran_conn_t conn, unsigned char * buf, s
   socklen_t srclen = (socklen_t) sizeof (src);
 
   msg_iov.iov_base = (void*) buf;
-  msg_iov.iov_len = len;
+  msg_iov.iov_len = (ddsi_iov_len_t)len; /* windows uses unsigned, POISX size_t */
 
   memset (&msghdr, 0, sizeof (msghdr));
 
diff --git a/src/core/ddsi/src/q_gc.c b/src/core/ddsi/src/q_gc.c
index 1e52830..3428b8c 100644
--- a/src/core/ddsi/src/q_gc.c
+++ b/src/core/ddsi/src/q_gc.c
@@ -98,14 +98,17 @@ static uint32_t gcreq_queue_thread (struct gcreq_queue *q)
       assert (trace_shortsleep);
       if (q->first == NULL)
       {
-        if (delay == T_NEVER)
-          os_condWait (&q->cond, &q->lock);
-        else
-        {
-          /* FIXME: fix os_time and use absolute timeouts */
-          struct os_time to = { delay / T_SECOND, delay % T_SECOND };
-          os_condTimedWait (&q->cond, &q->lock, &to);
+        /* FIXME: fix os_time and use absolute timeouts */
+        struct os_time to;
+        if (delay >= 1000 * T_SECOND) {
+          /* avoid overflow */
+          to.tv_sec = 1000;
+          to.tv_nsec = 0;
+        } else {
+          to.tv_sec = (os_timeSec)(delay / T_SECOND);
+          to.tv_nsec = (int32_t)(delay % T_SECOND);
         }
+        os_condTimedWait (&q->cond, &q->lock, &to);
       }
       if (q->first)
       {
diff --git a/src/core/ddsi/src/q_xmsg.c b/src/core/ddsi/src/q_xmsg.c
index 1643cb8..efdbc1a 100644
--- a/src/core/ddsi/src/q_xmsg.c
+++ b/src/core/ddsi/src/q_xmsg.c
@@ -1794,11 +1794,11 @@ int nn_xpack_addmsg (struct nn_xpack *xp, struct nn_xmsg *m, const uint32_t flag
 
   /* Append submessage; can possibly be merged with preceding iovec */
   if ((char *) xp->iov[niov-1].iov_base + xp->iov[niov-1].iov_len == (char *) m->data->payload)
-    xp->iov[niov-1].iov_len += m->sz;
+    xp->iov[niov-1].iov_len += (ddsi_iov_len_t)m->sz;
   else
   {
     xp->iov[niov].iov_base = m->data->payload;
-    xp->iov[niov].iov_len = m->sz;
+    xp->iov[niov].iov_len = (ddsi_iov_len_t)m->sz;
     niov++;
   }
   sz += m->sz;
diff --git a/src/core/ddsi/src/sysdeps.c b/src/core/ddsi/src/sysdeps.c
index 75c9702..90fc404 100644
--- a/src/core/ddsi/src/sysdeps.c
+++ b/src/core/ddsi/src/sysdeps.c
@@ -159,7 +159,7 @@ ssize_t sendmsg (os_handle fd, const struct msghdr *message, int flags)
   assert (message->msg_controllen == 0);
 #endif
 
-  if (WSASendTo (fd, (WSABUF *) message->msg_iov, message->msg_iovlen, &sent, flags, (SOCKADDR *) message->msg_name, message->msg_namelen, NULL, NULL) == 0)
+  if (WSASendTo (fd, (WSABUF *) message->msg_iov, (DWORD)message->msg_iovlen, &sent, flags, (SOCKADDR *) message->msg_name, message->msg_namelen, NULL, NULL) == 0)
     ret = (ssize_t) sent;
   else
     ret = -1;