diff --git a/mysql-test/r/ps.result b/mysql-test/r/ps.result
index 8a10a52ee65..482c9f42f42 100644
--- a/mysql-test/r/ps.result
+++ b/mysql-test/r/ps.result
@@ -1683,4 +1683,13 @@ execute stmt;
 ERROR 42S22: Unknown column 'y.value' in 'field list'
 deallocate prepare stmt;
 drop tables t1;
+prepare stmt from "create table t1 select ?";
+set @a=1.0;
+execute stmt using @a;
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `?` decimal(2,1) default NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+drop table t1;
 End of 5.0 tests.
diff --git a/mysql-test/t/ps.test b/mysql-test/t/ps.test
index 5b7adc40755..93a89c2b275 100644
--- a/mysql-test/t/ps.test
+++ b/mysql-test/t/ps.test
@@ -1791,5 +1791,13 @@ execute stmt;
 deallocate prepare stmt;
 drop tables t1;
 
+#
+# Bug #28509: strange behaviour: passing a decimal value to PS
+#
+prepare stmt from "create table t1 select ?";
+set @a=1.0;
+execute stmt using @a;
+show create table t1;
+drop table t1;
 
 --echo End of 5.0 tests.
diff --git a/sql/item.cc b/sql/item.cc
index 92ea35072f9..0f5d3c86485 100644
--- a/sql/item.cc
+++ b/sql/item.cc
@@ -2507,16 +2507,14 @@ bool Item_param::set_from_user_var(THD *thd, const user_var_entry *entry)
   if (entry && entry->value)
   {
     item_result_type= entry->type;
-    switch (entry->type) {
+    switch (item_result_type) {
     case REAL_RESULT:
       set_double(*(double*)entry->value);
       item_type= Item::REAL_ITEM;
-      item_result_type= REAL_RESULT;
       break;
     case INT_RESULT:
       set_int(*(longlong*)entry->value, MY_INT64_NUM_DECIMAL_DIGITS);
       item_type= Item::INT_ITEM;
-      item_result_type= INT_RESULT;
       break;
     case STRING_RESULT:
     {
@@ -2538,7 +2536,6 @@ bool Item_param::set_from_user_var(THD *thd, const user_var_entry *entry)
         charset of connection, so we have to set it later.
       */
       item_type= Item::STRING_ITEM;
-      item_result_type= STRING_RESULT;
 
       if (set_str((const char *)entry->value, entry->length))
         DBUG_RETURN(1);
@@ -2552,6 +2549,7 @@ bool Item_param::set_from_user_var(THD *thd, const user_var_entry *entry)
       decimals= ent_value->frac;
       max_length= my_decimal_precision_to_length(ent_value->precision(),
                                                  decimals, unsigned_flag);
+      item_type= Item::DECIMAL_ITEM;
       break;
     }
     default: