diff --git a/mysql-test/r/constraints.result b/mysql-test/r/constraints.result
index 3b41e291e0f..7cd8053c21b 100644
--- a/mysql-test/r/constraints.result
+++ b/mysql-test/r/constraints.result
@@ -14,3 +14,16 @@ drop table t1;
 create table t1 (a int null);
 insert into t1 values (1),(NULL);
 drop table t1;
+create table t1 (a int null);
+alter table t1 add constraint constraint_1 unique (a);
+alter table t1 add constraint unique key_1(a);
+alter table t1 add constraint constraint_2 unique key_2(a);
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `a` int(11) default NULL,
+  UNIQUE KEY `constraint_1` (`a`),
+  UNIQUE KEY `key_1` (`a`),
+  UNIQUE KEY `key_2` (`a`)
+) TYPE=MyISAM DEFAULT CHARSET=latin1
+drop table t1;
diff --git a/mysql-test/t/constraints.test b/mysql-test/t/constraints.test
index cc796e0abd2..dbc34a0dff1 100644
--- a/mysql-test/t/constraints.test
+++ b/mysql-test/t/constraints.test
@@ -21,3 +21,9 @@ drop table t1;
 create table t1 (a int null);
 insert into t1 values (1),(NULL);
 drop table t1;
+create table t1 (a int null);
+alter table t1 add constraint constraint_1 unique (a);
+alter table t1 add constraint unique key_1(a);
+alter table t1 add constraint constraint_2 unique key_2(a);
+show create table t1;
+drop table t1;
diff --git a/sql/sql_yacc.yy b/sql/sql_yacc.yy
index 805dc9f1932..8fe69ad6ae3 100644
--- a/sql/sql_yacc.yy
+++ b/sql/sql_yacc.yy
@@ -598,7 +598,7 @@ bool my_yyoverflow(short **a, YYSTYPE **b,int *yystacksize);
 
 %type <simple_string>
 	remember_name remember_end opt_ident opt_db text_or_password
-	opt_escape
+	opt_escape opt_constraint
 
 %type <string>
 	text_string opt_gconcat_separator
@@ -631,7 +631,7 @@ bool my_yyoverflow(short **a, YYSTYPE **b,int *yystacksize);
 	expr_list udf_expr_list when_list ident_list ident_list_arg
 
 %type <key_type>
-	key_type opt_unique_or_fulltext
+	key_type opt_unique_or_fulltext constraint_key_type
 
 %type <key_alg>
 	key_alg opt_btree_or_rtree
@@ -1189,6 +1189,13 @@ key_def:
 	    lex->key_list.push_back(new Key($1,$2, $3, lex->col_list));
 	    lex->col_list.empty();		/* Alloced by sql_alloc */
 	  }
+	| opt_constraint constraint_key_type opt_ident key_alg '(' key_list ')'
+	  {
+	    LEX *lex=Lex;
+	    const char *key_name= $3 ? $3:$1;
+	    lex->key_list.push_back(new Key($2, key_name, $4, lex->col_list));
+	    lex->col_list.empty();		/* Alloced by sql_alloc */
+	  }
 	| opt_constraint FOREIGN KEY_SYM opt_ident '(' key_list ')' references
 	  {
 	    LEX *lex=Lex;
@@ -1212,8 +1219,8 @@ check_constraint:
 	;
 
 opt_constraint:
-	/* empty */
-	| CONSTRAINT opt_ident;
+	/* empty */		{ $$=(char*) 0; }
+	| CONSTRAINT opt_ident	{ $$=$2; };
 
 field_spec:
 	field_ident
@@ -1575,14 +1582,16 @@ delete_option:
 	| SET DEFAULT    { $$= (int) foreign_key::FK_OPTION_DEFAULT;  };
 
 key_type:
-	opt_constraint PRIMARY_SYM KEY_SYM  { $$= Key::PRIMARY; }
-	| key_or_index			    { $$= Key::MULTIPLE; }
+	key_or_index			    { $$= Key::MULTIPLE; }
 	| FULLTEXT_SYM			    { $$= Key::FULLTEXT; }
 	| FULLTEXT_SYM key_or_index	    { $$= Key::FULLTEXT; }
 	| SPATIAL_SYM			    { $$= Key::SPATIAL; }
-	| SPATIAL_SYM key_or_index	    { $$= Key::SPATIAL; }
-	| opt_constraint UNIQUE_SYM	    { $$= Key::UNIQUE; }
-	| opt_constraint UNIQUE_SYM key_or_index { $$= Key::UNIQUE; };
+	| SPATIAL_SYM key_or_index	    { $$= Key::SPATIAL; };
+
+constraint_key_type:
+	PRIMARY_SYM KEY_SYM  { $$= Key::PRIMARY; }
+	| UNIQUE_SYM	    { $$= Key::UNIQUE; }
+	| UNIQUE_SYM key_or_index { $$= Key::UNIQUE; };
 
 key_or_index:
 	KEY_SYM {}