diff --git a/mysql-test/r/func_math.result b/mysql-test/r/func_math.result
index 525ee0dc506..ac24ef4dea9 100644
--- a/mysql-test/r/func_math.result
+++ b/mysql-test/r/func_math.result
@@ -521,6 +521,28 @@ CREATE TABLE t1 SELECT CEIL(LINESTRINGFROMWKB(1) DIV NULL);
 DROP TABLE t1;
 CREATE TABLE t1 SELECT FLOOR(LINESTRINGFROMWKB(1) DIV NULL);
 DROP TABLE t1;
+#
+# Bug#11765923  58937: MANY VALGRIND ERRORS AFTER GROUPING BY RESULT OF DECIMAL COLUMN FUNCTION
+#
+CREATE TABLE t1(f1 DECIMAL(22,1));
+INSERT INTO t1 VALUES (0),(1);
+SELECT ROUND(f1, f1) FROM t1;
+ROUND(f1, f1)
+0.0
+1.0
+SELECT ROUND(f1, f1) FROM t1 GROUP BY 1;
+ROUND(f1, f1)
+0.0
+1.0
+DROP TABLE t1;
+#
+# Bug#11764671  57533: UNINITIALISED VALUES IN COPY_AND_CONVERT (SQL_STRING.CC) WITH CERTAIN CHA
+#
+SELECT ROUND(LEAST(15, -4939092, 0.2704), STDDEV('a'));
+ROUND(LEAST(15, -4939092, 0.2704), STDDEV('a'))
+-4939092.0000
+Warnings:
+Warning	1292	Truncated incorrect DOUBLE value: 'a'
 End of 5.1 tests
 #
 # Bug #8433: Overflow must be an error
diff --git a/mysql-test/t/func_math.test b/mysql-test/t/func_math.test
index 687d96f8804..0e704fecf57 100644
--- a/mysql-test/t/func_math.test
+++ b/mysql-test/t/func_math.test
@@ -354,6 +354,22 @@ DROP TABLE t1;
 CREATE TABLE t1 SELECT FLOOR(LINESTRINGFROMWKB(1) DIV NULL);
 DROP TABLE t1;
 
+--echo #
+--echo # Bug#11765923  58937: MANY VALGRIND ERRORS AFTER GROUPING BY RESULT OF DECIMAL COLUMN FUNCTION
+--echo #
+
+CREATE TABLE t1(f1 DECIMAL(22,1));
+INSERT INTO t1 VALUES (0),(1);
+SELECT ROUND(f1, f1) FROM t1;
+SELECT ROUND(f1, f1) FROM t1 GROUP BY 1;
+DROP TABLE t1;
+
+--echo #
+--echo # Bug#11764671  57533: UNINITIALISED VALUES IN COPY_AND_CONVERT (SQL_STRING.CC) WITH CERTAIN CHA
+--echo #
+
+SELECT ROUND(LEAST(15, -4939092, 0.2704), STDDEV('a'));
+
 --echo End of 5.1 tests
 
 --echo #
diff --git a/sql/item_func.cc b/sql/item_func.cc
index 82310365d27..1388e0dc479 100644
--- a/sql/item_func.cc
+++ b/sql/item_func.cc
@@ -2407,10 +2407,7 @@ my_decimal *Item_func_round::decimal_op(my_decimal *decimal_value)
   if (!(null_value= (args[0]->null_value || args[1]->null_value ||
                      my_decimal_round(E_DEC_FATAL_ERROR, value, (int) dec,
                                       truncate, decimal_value) > 1))) 
-  {
-    decimal_value->frac= decimals;
     return decimal_value;
-  }
   return 0;
 }