diff --git a/lib/formdata.c b/lib/formdata.c
index 958e6cd2a234bb608331d7274f23a87341f75909..86c297745ebcd5110d648ce8e7f87c703a6baf3d 100644
--- a/lib/formdata.c
+++ b/lib/formdata.c
@@ -1279,7 +1279,7 @@ static size_t readfromfile(struct Form *form, char *buffer, size_t size)
     /* this file hasn't yet been opened */
     form->fp = fopen(form->data->line, "rb"); /* b is for binary */
     if(!form->fp)
-      return -1; /* failure */
+      return (size_t)-1; /* failure */
   }
   nread = fread(buffer, 1, size, form->fp);
 
diff --git a/lib/multi.c b/lib/multi.c
index ee7e388fa08de98f72e1416a6f8c3bb30a0b31df..c0f9a7918808c22938db04696dd3b252434319c9 100644
--- a/lib/multi.c
+++ b/lib/multi.c
@@ -780,7 +780,7 @@ static CURLMcode multi_runsingle(struct Curl_multi *multi,
           /* if we failed anywhere, we must clean up the secondary socket if
              it was used */
           sclose(easy->easy_conn->sock[SECONDARYSOCKET]);
-          easy->easy_conn->sock[SECONDARYSOCKET]=-1;
+          easy->easy_conn->sock[SECONDARYSOCKET] = CURL_SOCKET_BAD;
         }
         Curl_posttransfer(easy->easy_handle);
         Curl_done(&easy->easy_conn, easy->result);
diff --git a/lib/select.c b/lib/select.c
index 343dc469f7dd2f15f8b7865c6ea3b1ea753593e9..cf5f15a8f35bb22c30bd539c11b56edd0506c451 100644
--- a/lib/select.c
+++ b/lib/select.c
@@ -131,7 +131,7 @@ int Curl_select(curl_socket_t readfd, curl_socket_t writefd, int timeout_ms)
   timeout.tv_usec = (timeout_ms % 1000) * 1000;
 
   FD_ZERO(&fds_err);
-  maxfd = -1;
+  maxfd = (curl_socket_t)-1;
 
   FD_ZERO(&fds_read);
   if (readfd != CURL_SOCKET_BAD) {
@@ -206,7 +206,7 @@ int Curl_poll(struct pollfd ufds[], unsigned int nfds, int timeout_ms)
   FD_ZERO(&fds_read);
   FD_ZERO(&fds_write);
   FD_ZERO(&fds_err);
-  maxfd = -1;
+  maxfd = (curl_socket_t)-1;
 
   for (i = 0; i < nfds; i++) {
     if (ufds[i].fd == CURL_SOCKET_BAD)
diff --git a/lib/strerror.c b/lib/strerror.c
index b035e677253640ecf1f2c8aef5bb47fc5b11443c..faa750856c20ba082b9ba18aed15adfd384011e5 100644
--- a/lib/strerror.c
+++ b/lib/strerror.c
@@ -519,10 +519,11 @@ get_winsock_error (int err, char *buf, size_t len)
   case WSAEREMOTE:
     p = "Remote error";
     break;
+#ifdef WSAEDISCON  /* missing in SalfordC! */
   case WSAEDISCON:
     p = "Disconnected";
     break;
-
+#endif
     /* Extended Winsock errors */
   case WSASYSNOTREADY:
     p = "Winsock library is not ready";