diff --git a/usr.bin/patch/pch.c b/usr.bin/patch/pch.c
index 411dcac0c931..c4792b203540 100644
--- a/usr.bin/patch/pch.c
+++ b/usr.bin/patch/pch.c
@@ -101,13 +101,17 @@ void
 open_patch_file(const char *filename)
 {
 	struct stat filestat;
+	int nr, nw;
 
 	if (filename == NULL || *filename == '\0' || strEQ(filename, "-")) {
 		pfp = fopen(TMPPATNAME, "w");
 		if (pfp == NULL)
 			pfatal("can't create %s", TMPPATNAME);
-		while (fgets(buf, buf_size, stdin) != NULL)
-			fputs(buf, pfp);
+		while ((nr = fread(buf, 1, buf_size, stdin)) > 0) {
+			nw = fwrite(buf, 1, nr, pfp);
+			if (nr != nw)
+				pfatal("write error to %s", TMPPATNAME);
+		}
 		if (ferror(pfp) || fclose(pfp))
 			pfatal("can't write %s", TMPPATNAME);
 		filename = TMPPATNAME;