diff --git a/server/request.c b/server/request.c
index 597bf886c84..b937e6f06a4 100644
--- a/server/request.c
+++ b/server/request.c
@@ -241,7 +241,7 @@ void write_reply( struct thread *thread )
     }
     if (errno == EPIPE)
         kill_thread( thread, 0 );  /* normal death */
-    else if (errno != EWOULDBLOCK && errno != EAGAIN)
+    else if (errno != EWOULDBLOCK && (EWOULDBLOCK == EAGAIN || errno != EAGAIN))
         fatal_protocol_error( thread, "reply write: %s\n", strerror( errno ));
 }
 
@@ -368,7 +368,7 @@ error:
         kill_thread( thread, 0 );
     else if (ret > 0)
         fatal_protocol_error( thread, "partial read %d\n", ret );
-    else if (errno != EWOULDBLOCK && errno != EAGAIN)
+    else if (errno != EWOULDBLOCK && (EWOULDBLOCK == EAGAIN || errno != EAGAIN))
         fatal_protocol_error( thread, "read: %s\n", strerror( errno ));
 }
 
@@ -449,7 +449,7 @@ int receive_fd( struct process *process )
     }
     else
     {
-        if (errno != EWOULDBLOCK && errno != EAGAIN)
+        if (errno != EWOULDBLOCK && (EWOULDBLOCK == EAGAIN || errno != EAGAIN))
         {
             fprintf( stderr, "Protocol error: process %04x: ", process->id );
             perror( "recvmsg" );
diff --git a/server/sock.c b/server/sock.c
index dc10d2a415f..89049e0e878 100644
--- a/server/sock.c
+++ b/server/sock.c
@@ -1075,8 +1075,8 @@ static void ifchange_poll_event( struct fd *fd, int event )
     r = recv( get_unix_fd(fd), buffer, sizeof(buffer), MSG_DONTWAIT );
     if (r < 0)
     {
-        if (errno == EWOULDBLOCK || errno == EAGAIN)
-            return; /* retry when poll() says the socket is ready */
+        if (errno == EWOULDBLOCK || (EWOULDBLOCK != EAGAIN && errno == EAGAIN))
+            return;  /* retry when poll() says the socket is ready */
         status = sock_get_ntstatus( errno );
     }
     else if (r > 0)