diff --git a/evutil.c b/evutil.c
index e8f5b96d..ce3ef31c 100644
--- a/evutil.c
+++ b/evutil.c
@@ -323,9 +323,11 @@ evutil_make_socket_nonblocking(evutil_socket_t fd)
 			event_warn("fcntl(%d, F_GETFL)", fd);
 			return -1;
 		}
-		if (fcntl(fd, F_SETFL, flags | O_NONBLOCK) == -1) {
-			event_warn("fcntl(%d, F_SETFL)", fd);
-			return -1;
+		if (!(flags & O_NONBLOCK)) {
+			if (fcntl(fd, F_SETFL, flags | O_NONBLOCK) == -1) {
+				event_warn("fcntl(%d, F_SETFL)", fd);
+				return -1;
+			}
 		}
 	}
 #endif