diff --git a/mysql-test/r/merge.result b/mysql-test/r/merge.result
index 184cd92e053..dbffbba1b8b 100644
--- a/mysql-test/r/merge.result
+++ b/mysql-test/r/merge.result
@@ -2286,4 +2286,16 @@ m1	CREATE TABLE `m1` (
 DROP TABLE m1;
 DROP TABLE `test@1`.`t@1`;
 DROP DATABASE `test@1`;
+#
+# Bug#51494c rash with join, explain and 'sounds like' operator
+#
+CREATE TABLE t1 (a INT) ENGINE=MYISAM;
+INSERT INTO t1 VALUES(1);
+CREATE TABLE t2 (b INT NOT NULL,c INT,d INT,e BLOB NOT NULL,
+KEY idx0 (d, c)) ENGINE=MERGE;
+EXPLAIN SELECT * FROM t1 NATURAL RIGHT JOIN
+t2 WHERE b SOUNDS LIKE e AND d = 1;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE noticed after reading const tables
+DROP TABLE t2, t1;
 End of 5.1 tests
diff --git a/mysql-test/t/merge.test b/mysql-test/t/merge.test
index d88467cc7a9..44b202fab97 100644
--- a/mysql-test/t/merge.test
+++ b/mysql-test/t/merge.test
@@ -1690,4 +1690,19 @@ DROP TABLE m1;
 DROP TABLE `test@1`.`t@1`;
 DROP DATABASE `test@1`;
 
+--echo #
+--echo # Bug#51494c rash with join, explain and 'sounds like' operator
+--echo #
+
+CREATE TABLE t1 (a INT) ENGINE=MYISAM;
+INSERT INTO t1 VALUES(1);
+
+CREATE TABLE t2 (b INT NOT NULL,c INT,d INT,e BLOB NOT NULL,
+KEY idx0 (d, c)) ENGINE=MERGE;
+
+EXPLAIN SELECT * FROM t1 NATURAL RIGHT JOIN
+t2 WHERE b SOUNDS LIKE e AND d = 1;
+
+DROP TABLE t2, t1;
+
 --echo End of 5.1 tests
diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index 055246ee0df..b3640f9dd22 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -2943,7 +2943,8 @@ make_join_statistics(JOIN *join, TABLE_LIST *tables_arg, COND *conds,
       s->quick=select->quick;
       s->needed_reg=select->needed_reg;
       select->quick=0;
-      if (records == 0 && s->table->reginfo.impossible_range)
+      if (records == 0 && s->table->reginfo.impossible_range &&
+          (s->table->file->ha_table_flags() & HA_STATS_RECORDS_IS_EXACT))
       {
 	/*
 	  Impossible WHERE or ON expression