diff --git a/README.cygwin b/README.cygwin
index c09eeaba6a52..99d0a4f5983b 100644
--- a/README.cygwin
+++ b/README.cygwin
@@ -401,8 +401,9 @@ Win9x can not rename() an open file (although WinNT can).
 The Cygwin chroot() implementation has holes (it can not restrict file
 access by native Win32 programs).
 
-Inplace editing ( perl -i ) of files doesn't work without doing a backup 
-of the file being edited ( perl -i.bak ).
+Inplace editing C<perl -i> of files doesn't work without doing a backup 
+of the file being edited C<perl -i.bak> because of windowish restrictions,
+so Perl does this automagically if you just use C<perl -i>.
 
 =back
 
diff --git a/doio.c b/doio.c
index e209cf298138..95ae169b48fe 100644
--- a/doio.c
+++ b/doio.c
@@ -790,7 +790,7 @@ Perl_nextargv(pTHX_ register GV *gv)
 #endif
 		}
 		else {
-#if !defined(DOSISH) && !defined(AMIGAOS) && !defined(__CYGWIN__)
+#if !defined(DOSISH) && !defined(AMIGAOS)
 #  ifndef VMS  /* Don't delete; use automatic file versioning */
 		    if (UNLINK(PL_oldname) < 0) {
 		        if (ckWARN_d(WARN_INPLACE))	
diff --git a/perl.c b/perl.c
index 90b227eafb46..2354ce5eb375 100644
--- a/perl.c
+++ b/perl.c
@@ -2363,6 +2363,12 @@ Perl_moreswitches(pTHX_ char *s)
     case 'i':
 	if (PL_inplace)
 	    Safefree(PL_inplace);
+#if defined(__CYGWIN__) /* do backup extension automagically */
+	if (*(s+1) == '\0') {
+	PL_inplace = savepv(".bak");
+	return s+1;
+	}
+#endif /* __CYGWIN__ */
 	PL_inplace = savepv(s+1);
 	/*SUPPRESS 530*/
 	for (s = PL_inplace; *s && !isSPACE(*s); s++) ;