diff --git a/mysql-test/r/join_cache.result b/mysql-test/r/join_cache.result
index 3c352386b8a..d04a1aaf6a2 100644
--- a/mysql-test/r/join_cache.result
+++ b/mysql-test/r/join_cache.result
@@ -5589,4 +5589,30 @@ i
 6
 SET SESSION join_cache_level = DEFAULT;
 DROP TABLE t1,t2;
+#
+# Bug #669382: hash join using a ref with constant key parts 
+#
+CREATE TABLE t1 (a int);
+INSERT INTO t1 VALUES
+(9), (11), (7), (8), (4), (1), (12), (3), (5);
+INSERT INTO t1 SELECT * FROM t1;
+INSERT INTO t1 SELECT * FROM t1;
+CREATE TABLE t2 (a int, b int, c int, INDEX idx (a,b));
+INSERT INTO t2 VALUES
+(8, 80, 800), (1, 10, 100), (1, 11, 101), (3, 30, 300),
+(1, 12, 102), (8, 81, 801), (7, 70, 700), (12, 120, 1200),
+(8, 82, 802), (1, 13, 103), (1, 14, 104), (3, 31, 301),
+(1, 15, 105), (8, 83, 803), (7, 71, 701);
+SET SESSION join_cache_level = 4;
+SET SESSION join_buffer_size = 192;
+EXPLAIN
+SELECT t1.a, t2.c FROM t1,t2 WHERE t1.a=t2.a AND t2.b=99;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	36	Using where
+1	SIMPLE	t2	ref	idx	idx	10	test.t1.a,const	2	Using join buffer (flat, BNLH join)
+SELECT t1.a, t2.c FROM t1,t2 WHERE t1.a=t2.a AND t2.b=99;
+a	c
+SET SESSION join_cache_level = DEFAULT;
+SET SESSION join_buffer_size = DEFAULT;
+DROP TABLE t1,t2;
 set @@optimizer_switch=@save_optimizer_switch;
diff --git a/mysql-test/t/join_cache.test b/mysql-test/t/join_cache.test
index 48a2cd1d4a8..16bd2d515ad 100644
--- a/mysql-test/t/join_cache.test
+++ b/mysql-test/t/join_cache.test
@@ -2286,5 +2286,34 @@ SET SESSION join_cache_level = DEFAULT;
 
 DROP TABLE t1,t2;
 
+--echo #
+--echo # Bug #669382: hash join using a ref with constant key parts 
+--echo #
+
+CREATE TABLE t1 (a int);
+INSERT INTO t1 VALUES
+  (9), (11), (7), (8), (4), (1), (12), (3), (5);
+INSERT INTO t1 SELECT * FROM t1;
+INSERT INTO t1 SELECT * FROM t1;
+
+CREATE TABLE t2 (a int, b int, c int, INDEX idx (a,b));
+INSERT INTO t2 VALUES
+  (8, 80, 800), (1, 10, 100), (1, 11, 101), (3, 30, 300),
+  (1, 12, 102), (8, 81, 801), (7, 70, 700), (12, 120, 1200),
+  (8, 82, 802), (1, 13, 103), (1, 14, 104), (3, 31, 301),
+  (1, 15, 105), (8, 83, 803), (7, 71, 701);
+
+SET SESSION join_cache_level = 4;
+SET SESSION join_buffer_size = 192;
+
+EXPLAIN
+SELECT t1.a, t2.c FROM t1,t2 WHERE t1.a=t2.a AND t2.b=99; 
+SELECT t1.a, t2.c FROM t1,t2 WHERE t1.a=t2.a AND t2.b=99; 
+
+SET SESSION join_cache_level = DEFAULT;
+SET SESSION join_buffer_size = DEFAULT;
+
+DROP TABLE t1,t2;
+
 # this must be the last command in the file
 set @@optimizer_switch=@save_optimizer_switch;
diff --git a/sql/sql_join_cache.cc b/sql/sql_join_cache.cc
index 3586426419d..6dce5884c9a 100644
--- a/sql/sql_join_cache.cc
+++ b/sql/sql_join_cache.cc
@@ -2500,6 +2500,9 @@ int JOIN_CACHE_HASHED::init()
   if ((rc= JOIN_CACHE::init()))
     DBUG_RETURN (rc);
 
+  if (!(key_buff= (uchar*) sql_alloc(key_length)))
+    DBUG_RETURN(1);
+
   /* Take into account a reference to the next record in the key chain */
   pack_length+= get_size_of_rec_offset(); 
   pack_length_with_blob_ptrs+= get_size_of_rec_offset();
@@ -3300,9 +3303,9 @@ uchar *JOIN_CACHE_BNLH::get_matching_chain_by_join_key()
   TABLE_REF *ref= &join_tab->ref;
   KEY *keyinfo= table->key_info+ref->key;
   /* Build the join key value out of the record in the record buffer */
-  key_copy(ref->key_buff, table->record[0], keyinfo, ref->key_length);
+  key_copy(key_buff, table->record[0], keyinfo, key_length);
   /* Look for this key in the join buffer */
-  if (!key_search(ref->key_buff, ref->key_length, &key_ref_ptr))
+  if (!key_search(key_buff, key_length, &key_ref_ptr))
     return 0;
   return key_ref_ptr+get_size_of_key_offset();
 }
diff --git a/sql/sql_select.h b/sql/sql_select.h
index 74b93c1d37c..10122b02e04 100644
--- a/sql/sql_select.h
+++ b/sql/sql_select.h
@@ -1133,11 +1133,6 @@ private:
   /* Size of the offset of a key entry in the hash table */
   uint size_of_key_ofs;
 
-  /* 
-    Length of a key value.
-    It is assumed that all key values have the same length.
-  */
-  uint key_length;
   /* 
     Length of the key entry in the hash table.
     A key entry either contains the key value, or it contains a reference
@@ -1164,6 +1159,14 @@ private:
   
 protected:
 
+  /* 
+    Length of a key value.
+    It is assumed that all key values have the same length.
+  */
+  uint key_length;
+  /* Buffer to store key values for probing */
+  uchar *key_buff;
+
   /* Number of key entries in the hash table (number of distinct keys) */
   uint key_entries;