diff --git a/ChangeLog b/ChangeLog
index 86785dbecc..23d91f41b1 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Wed Jun 23 06:42:08 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* io.c (argf_next_argv): check for setting owner/group.
+
 Tue Jun 22 23:10:10 2010  Tanaka Akira  <akr@fsij.org>
 
 	* time.c (num_exact): fix for mathn.  [ruby-dev:41599]
diff --git a/io.c b/io.c
index d231e1317c..68f6a96522 100644
--- a/io.c
+++ b/io.c
@@ -6818,11 +6818,21 @@ argf_next_argv(VALUE argf)
 		    chmod(fn, st.st_mode);
 #endif
 		    if (st.st_uid!=st2.st_uid || st.st_gid!=st2.st_gid) {
+			int err;
 #ifdef HAVE_FCHOWN
-			(void)fchown(fw, st.st_uid, st.st_gid);
+			err = fchown(fw, st.st_uid, st.st_gid);
 #else
-			(void)chown(fn, st.st_uid, st.st_gid);
+			err = chown(fn, st.st_uid, st.st_gid);
 #endif
+			if (err && getuid() == 0 && st2.st_uid == 0) {
+			    const char *wkfn = RSTRING_PTR(ARGF.filename);
+			    rb_warn("Can't set owner/group of %s to same as %s: %s, skipping file",
+				    wkfn, fn, strerror(errno));
+			    (void)close(fr);
+			    (void)close(fw);
+			    (void)unlink(wkfn);
+			    goto retry;
+			}
 		    }
 #endif
 		    rb_stdout = prep_io(fw, FMODE_WRITABLE, rb_cFile, fn);
diff --git a/version.h b/version.h
index 2209aced93..5ea41f281b 100644
--- a/version.h
+++ b/version.h
@@ -1,5 +1,5 @@
 #define RUBY_VERSION "1.9.3"
-#define RUBY_RELEASE_DATE "2010-06-22"
+#define RUBY_RELEASE_DATE "2010-06-23"
 #define RUBY_PATCHLEVEL -1
 #define RUBY_BRANCH_NAME "trunk"
 
@@ -8,7 +8,7 @@
 #define RUBY_VERSION_TEENY 1
 #define RUBY_RELEASE_YEAR 2010
 #define RUBY_RELEASE_MONTH 6
-#define RUBY_RELEASE_DAY 22
+#define RUBY_RELEASE_DAY 23
 
 #include "ruby/version.h"