--- /dev/null
+diff -up patch-2.6.1/src/patch.c.backup-if-mismatch patch-2.6.1/src/patch.c
+--- patch-2.6.1/src/patch.c.backup-if-mismatch 2011-02-16 16:43:54.575850844 +0000
++++ patch-2.6.1/src/patch.c 2011-02-16 16:44:56.907995789 +0000
+@@ -106,6 +106,7 @@ main (int argc, char **argv)
+ char numbuf[LINENUM_LENGTH_BOUND + 1];
+ bool written_to_rejname = false;
+ bool apply_empty_patch = false;
++ bool posixly_correct_set;
+
+ exit_failure = 2;
+ program_name = argv[0];
+@@ -125,7 +126,7 @@ main (int argc, char **argv)
+ i < 0 ? shell_quoting_style : (enum quoting_style) i);
+ }
+
+- posixly_correct = getenv ("POSIXLY_CORRECT") != 0;
++ posixly_correct_set = posixly_correct = getenv ("POSIXLY_CORRECT") != 0;
+ backup_if_mismatch = ! posixly_correct;
+ patch_get = ((val = getenv ("PATCH_GET"))
+ ? numeric_string (val, true, "PATCH_GET value")
+@@ -151,6 +152,10 @@ main (int argc, char **argv)
+ Argv = argv;
+ get_some_switches();
+
++ /* Let --posix cause --no-backup-if-mismatch. */
++ if (! posixly_correct_set && posixly_correct && backup_if_mismatch)
++ backup_if_mismatch = false;
++
+ if (make_backups | backup_if_mismatch)
+ backup_type = get_version (version_control_context, version_control);
+