diff --git a/mysql-test/r/func_time.result b/mysql-test/r/func_time.result
index 4ff4cfa586b..48e837f180f 100644
--- a/mysql-test/r/func_time.result
+++ b/mysql-test/r/func_time.result
@@ -1343,4 +1343,18 @@ SELECT 1 FROM t1 ORDER BY @x:=makedate(a,a);
 1
 1
 DROP TABLE t1;
+#
+# Bug #52160: crash and inconsistent results when grouping
+#             by a function and column
+#
+CREATE TABLE t1(a CHAR(10) NOT NULL);
+INSERT INTO t1 VALUES (''),('');
+SELECT COUNT(*) FROM t1 GROUP BY TIME_TO_SEC(a);
+COUNT(*)
+2
+Warnings:
+Warning	1292	Truncated incorrect time value: ''
+Warning	1292	Truncated incorrect time value: ''
+Warning	1292	Truncated incorrect time value: ''
+DROP TABLE t1;
 End of 5.1 tests
diff --git a/mysql-test/r/type_blob.result b/mysql-test/r/type_blob.result
index 08c30d884fd..e6fd49b4247 100644
--- a/mysql-test/r/type_blob.result
+++ b/mysql-test/r/type_blob.result
@@ -974,3 +974,14 @@ ERROR 42000: Display width out of range for column 'cast as char' (max = 4294967
 explain select convert(1, binary(999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999));
 ERROR 42000: Display width out of range for column 'cast as char' (max = 4294967295)
 End of 5.0 tests
+# Bug #52160: crash and inconsistent results when grouping
+#             by a function and column
+CREATE FUNCTION f1() RETURNS TINYBLOB RETURN 1;
+CREATE TABLE t1(a CHAR(1));
+INSERT INTO t1 VALUES ('0'), ('0');
+SELECT COUNT(*) FROM t1 GROUP BY f1(), a;
+COUNT(*)
+2
+DROP FUNCTION f1;
+DROP TABLE t1;
+End of 5.1 tests
diff --git a/mysql-test/t/func_time.test b/mysql-test/t/func_time.test
index e764906c374..8fce7072319 100644
--- a/mysql-test/t/func_time.test
+++ b/mysql-test/t/func_time.test
@@ -849,4 +849,14 @@ INSERT INTO t1 VALUES (0),(9.216e-096);
 SELECT 1 FROM t1 ORDER BY @x:=makedate(a,a);
 DROP TABLE t1;
 
+--echo #
+--echo # Bug #52160: crash and inconsistent results when grouping
+--echo #             by a function and column
+--echo #
+
+CREATE TABLE t1(a CHAR(10) NOT NULL);
+INSERT INTO t1 VALUES (''),('');
+SELECT COUNT(*) FROM t1 GROUP BY TIME_TO_SEC(a);
+DROP TABLE t1;
+
 --echo End of 5.1 tests
diff --git a/mysql-test/t/type_blob.test b/mysql-test/t/type_blob.test
index 460da1c1614..4e097edf73d 100644
--- a/mysql-test/t/type_blob.test
+++ b/mysql-test/t/type_blob.test
@@ -612,3 +612,19 @@ explain select convert(1, binary(4294967296));
 explain select convert(1, binary(999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999));
 
 --echo End of 5.0 tests
+
+--echo # Bug #52160: crash and inconsistent results when grouping
+--echo #             by a function and column
+
+CREATE FUNCTION f1() RETURNS TINYBLOB RETURN 1;
+
+CREATE TABLE t1(a CHAR(1));
+INSERT INTO t1 VALUES ('0'), ('0');
+
+SELECT COUNT(*) FROM t1 GROUP BY f1(), a;
+
+DROP FUNCTION f1;
+DROP TABLE t1;
+
+--echo End of 5.1 tests
+
diff --git a/sql/item_timefunc.h b/sql/item_timefunc.h
index ef86406e1be..47bb9509582 100644
--- a/sql/item_timefunc.h
+++ b/sql/item_timefunc.h
@@ -331,6 +331,7 @@ public:
   const char *func_name() const { return "time_to_sec"; }
   void fix_length_and_dec()
   {
+    maybe_null= TRUE;
     decimals=0;
     max_length=10*MY_CHARSET_BIN_MB_MAXLEN;
   }
diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index 08bd0c28738..77d4447fd0f 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -15198,6 +15198,8 @@ calc_group_buffer(JOIN *join,ORDER *group)
         {
           key_length+= 8;
         }
+        else if (type == MYSQL_TYPE_BLOB)
+          key_length+= MAX_BLOB_WIDTH;		// Can't be used as a key
         else
         {
           /*