diff --git a/mysql-test/r/heap.result b/mysql-test/r/heap.result
index 29207a4ae98..53dec294ef8 100644
--- a/mysql-test/r/heap.result
+++ b/mysql-test/r/heap.result
@@ -291,3 +291,8 @@ a	b
 1	7
 1	8
 drop table t1;
+create table t1 (c char(255), primary key(c(90)));
+insert into t1 values ("abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz");
+insert into t1 values ("abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz");
+ERROR 23000: Duplicate entry 'abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijkl' for key 1
+drop table t1;
diff --git a/mysql-test/t/heap.test b/mysql-test/t/heap.test
index e082993a58e..c0977819487 100644
--- a/mysql-test/t/heap.test
+++ b/mysql-test/t/heap.test
@@ -224,3 +224,12 @@ insert t1 (a) values (1);
 insert t1 (a) values (1);
 select * from t1;                                                               
 drop table t1;
+
+#
+# Bug #10566: Verify that we can create a prefixed key with length > 255
+#
+create table t1 (c char(255), primary key(c(90)));
+insert into t1 values ("abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz");
+--error 1062
+insert into t1 values ("abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz");
+drop table t1;
diff --git a/sql/ha_heap.h b/sql/ha_heap.h
index 60e2e84c5d2..33de0156074 100644
--- a/sql/ha_heap.h
+++ b/sql/ha_heap.h
@@ -53,6 +53,7 @@ public:
   }
   const key_map *keys_to_use_for_scanning() { return &btree_keys; }
   uint max_supported_keys()          const { return MAX_KEY; }
+  uint max_supported_key_part_length() const { return MAX_KEY_LENGTH; }
   double scan_time() { return (double) (records+deleted) / 20.0+10; }
   double read_time(uint index, uint ranges, ha_rows rows)
   { return (double) rows /  20.0+1; }