diff --git a/[refs] b/[refs]
index 41363a66415f..b1d07ad16793 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: c2b7a4bb30008dc256d63802e02b6fb950958443
+refs/heads/master: 190f4939222b8c07cd62a20e1ce0c7a97fffde99
diff --git a/trunk/arch/um/os-Linux/mem.c b/trunk/arch/um/os-Linux/mem.c
index d24d1a960523..560c8063c77c 100644
--- a/trunk/arch/um/os-Linux/mem.c
+++ b/trunk/arch/um/os-Linux/mem.c
@@ -210,8 +210,11 @@ int create_tmp_file(unsigned long long len)
 		exit(1);
 	}
 
-        if (lseek64(fd, len, SEEK_SET) < 0) {
- 		perror("os_seek_file");
+	/* Seek to len - 1 because writing a character there will
+	 * increase the file size by one byte, to the desired length.
+	 */
+	if (lseek64(fd, len - 1, SEEK_SET) < 0) {
+		perror("os_seek_file");
 		exit(1);
 	}