diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/mathExpressions.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/mathExpressions.scala
index c4d47ab2084fd..de1a46dc47805 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/mathExpressions.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/mathExpressions.scala
@@ -1023,10 +1023,10 @@ abstract class RoundBase(child: Expression, scale: Expression,
 
   // not overriding since _scale is a constant int at runtime
   def nullSafeEval(input1: Any): Any = {
-    child.dataType match {
-      case _: DecimalType =>
+    dataType match {
+      case DecimalType.Fixed(_, s) =>
         val decimal = input1.asInstanceOf[Decimal]
-        decimal.toPrecision(decimal.precision, _scale, mode).orNull
+        decimal.toPrecision(decimal.precision, s, mode).orNull
       case ByteType =>
         BigDecimal(input1.asInstanceOf[Byte]).setScale(_scale, mode).toByte
       case ShortType =>
@@ -1055,10 +1055,10 @@ abstract class RoundBase(child: Expression, scale: Expression,
   override def doGenCode(ctx: CodegenContext, ev: ExprCode): ExprCode = {
     val ce = child.genCode(ctx)
 
-    val evaluationCode = child.dataType match {
-      case _: DecimalType =>
+    val evaluationCode = dataType match {
+      case DecimalType.Fixed(_, s) =>
         s"""
-        if (${ce.value}.changePrecision(${ce.value}.precision(), ${_scale},
+        if (${ce.value}.changePrecision(${ce.value}.precision(), ${s},
             java.math.BigDecimal.${modeStr})) {
           ${ev.value} = ${ce.value};
         } else {
diff --git a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/MathExpressionsSuite.scala b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/MathExpressionsSuite.scala
index 6b5bfac94645c..1555dd1cf58d4 100644
--- a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/MathExpressionsSuite.scala
+++ b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/MathExpressionsSuite.scala
@@ -546,15 +546,14 @@ class MathExpressionsSuite extends SparkFunSuite with ExpressionEvalHelper {
     val bdResults: Seq[BigDecimal] = Seq(BigDecimal(3.0), BigDecimal(3.1), BigDecimal(3.14),
       BigDecimal(3.142), BigDecimal(3.1416), BigDecimal(3.14159),
       BigDecimal(3.141593), BigDecimal(3.1415927))
-    // round_scale > current_scale would result in precision increase
-    // and not allowed by o.a.s.s.types.Decimal.changePrecision, therefore null
+
     (0 to 7).foreach { i =>
       checkEvaluation(Round(bdPi, i), bdResults(i), EmptyRow)
       checkEvaluation(BRound(bdPi, i), bdResults(i), EmptyRow)
     }
     (8 to 10).foreach { scale =>
-      checkEvaluation(Round(bdPi, scale), null, EmptyRow)
-      checkEvaluation(BRound(bdPi, scale), null, EmptyRow)
+      checkEvaluation(Round(bdPi, scale), bdPi, EmptyRow)
+      checkEvaluation(BRound(bdPi, scale), bdPi, EmptyRow)
     }
 
     DataTypeTestUtils.numericTypes.foreach { dataType =>
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/MathFunctionsSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/MathFunctionsSuite.scala
index 328c5395ec91e..c2d08a06569bf 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/MathFunctionsSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/MathFunctionsSuite.scala
@@ -231,6 +231,19 @@ class MathFunctionsSuite extends QueryTest with SharedSQLContext {
       Seq(Row(BigDecimal("0E3"), BigDecimal("0E2"), BigDecimal("0E1"), BigDecimal(3),
         BigDecimal("3.1"), BigDecimal("3.14"), BigDecimal("3.142")))
     )
+
+    val bdPi: BigDecimal = BigDecimal(31415925L, 7)
+    checkAnswer(
+      sql(s"SELECT round($bdPi, 7), round($bdPi, 8), round($bdPi, 9), round($bdPi, 10), " +
+        s"round($bdPi, 100), round($bdPi, 6), round(null, 8)"),
+      Seq(Row(bdPi, bdPi, bdPi, bdPi, bdPi, BigDecimal("3.141593"), null))
+    )
+
+    checkAnswer(
+      sql(s"SELECT bround($bdPi, 7), bround($bdPi, 8), bround($bdPi, 9), bround($bdPi, 10), " +
+        s"bround($bdPi, 100), bround($bdPi, 6), bround(null, 8)"),
+      Seq(Row(bdPi, bdPi, bdPi, bdPi, bdPi, BigDecimal("3.141592"), null))
+    )
   }
 
   test("round/bround with data frame from a local Seq of Product") {