--- /dev/null
+++ b/mysql-test/r/percona_bug933969.result
@@ -0,0 +1,16 @@
+RESET MASTER;
+DROP TABLE IF EXISTS t1;
+CREATE TABLE t1 (word VARCHAR(20));
+INSERT INTO t1 VALUES ("hamite");
+INSERT INTO t1 VALUES ("hoho");
+INSERT INTO t1 VALUES ("znamenito");
+INSERT INTO t1 VALUES ("mrachny");
+INSERT INTO t1 VALUES ("mrak");
+INSERT INTO t1 VALUES ("zhut");
+INSERT INTO t1 VALUES ("parnisha");
+INSERT INTO t1 VALUES ("krrasota!");
+INSERT INTO t1 VALUES ("podumayesh");
+INSERT INTO t1 VALUES ("ogo!");
+FLUSH LOGS;
+DROP TABLE t1;
+RESET MASTER;
--- /dev/null
+++ b/mysql-test/t/percona_bug933969.test
@@ -0,0 +1,42 @@
+###################### percona_bug933969.test ########################
+# Bug #933969: mysqlbinlog doesn't accept stdin                      #
+#                                                                    #
+# The goal of this testcase is to test that mysqlbinlog handle       #
+# stdin correctly when stdin is pipe.                                #
+# i.e. "cat log | mysqlbinlog -" don't cause mysqlbinlog failure     #
+######################################################################
+-- source include/have_log_bin.inc
+-- source include/not_windows.inc
+-- source include/not_embedded.inc
+
+# deletes all the binary logs
+RESET MASTER;
+
+--disable_warnings
+DROP TABLE IF EXISTS t1;
+--enable_warnings
+
+# produce some statements for binlog
+
+CREATE TABLE t1 (word VARCHAR(20));
+
+INSERT INTO t1 VALUES ("hamite");
+INSERT INTO t1 VALUES ("hoho");
+INSERT INTO t1 VALUES ("znamenito");
+INSERT INTO t1 VALUES ("mrachny");
+INSERT INTO t1 VALUES ("mrak");
+INSERT INTO t1 VALUES ("zhut");
+INSERT INTO t1 VALUES ("parnisha");
+INSERT INTO t1 VALUES ("krrasota!");
+INSERT INTO t1 VALUES ("podumayesh");
+INSERT INTO t1 VALUES ("ogo!");
+
+FLUSH LOGS;
+
+# run mysqlbinlog and make sure it ends normally
+
+let $MYSQLD_DATADIR= `SELECT @@datadir`;
+--system cat $MYSQLD_DATADIR/master-bin.000001 | $MYSQL_BINLOG - >/dev/null
+
+DROP TABLE t1;
+RESET MASTER;
--- a/client/mysqlbinlog.cc
+++ b/client/mysqlbinlog.cc
@@ -1760,7 +1760,7 @@
   }
 
   pos= my_b_tell(file);
-  my_b_seek(file, (my_off_t)0);
+  DBUG_ASSERT(pos == 0);
   if (my_b_read(file, header, sizeof(header)))
   {
     error("Failed reading header; probably an empty file.");
@@ -1920,7 +1920,7 @@
     /* read from normal file */
     if ((fd = my_open(logname, O_RDONLY | O_BINARY, MYF(MY_WME))) < 0)
       return ERROR_STOP;
-    if (init_io_cache(file, fd, 0, READ_CACHE, start_position_mot, 0,
+    if (init_io_cache(file, fd, 0, READ_CACHE, (my_off_t) 0, 0,
 		      MYF(MY_WME | MY_NABP)))
     {
       my_close(fd, MYF(MY_WME));
@@ -1928,6 +1928,7 @@
     }
     if ((retval= check_header(file, print_event_info, logname)) != OK_CONTINUE)
       goto end;
+    my_b_seek(file, start_position_mot);
   }
   else
   {