diff --git a/src/main/scala/edu/berkeley/cs/rise/opaque/Utils.scala b/src/main/scala/edu/berkeley/cs/rise/opaque/Utils.scala
index 641223a62d..cb054a3d36 100644
--- a/src/main/scala/edu/berkeley/cs/rise/opaque/Utils.scala
+++ b/src/main/scala/edu/berkeley/cs/rise/opaque/Utils.scala
@@ -73,7 +73,6 @@ import org.apache.spark.sql.catalyst.expressions.SortOrder
 import org.apache.spark.sql.catalyst.expressions.StartsWith
 import org.apache.spark.sql.catalyst.expressions.Substring
 import org.apache.spark.sql.catalyst.expressions.Subtract
-import org.apache.spark.sql.catalyst.expressions.TimeAdd
 import org.apache.spark.sql.catalyst.expressions.UnaryMinus
 import org.apache.spark.sql.catalyst.expressions.Upper
 import org.apache.spark.sql.catalyst.expressions.Year
@@ -109,6 +108,8 @@ import edu.berkeley.cs.rise.opaque.expressions.VectorMultiply
 import edu.berkeley.cs.rise.opaque.expressions.VectorSum
 import edu.berkeley.cs.rise.opaque.logical.ConvertToOpaqueOperators
 import edu.berkeley.cs.rise.opaque.logical.EncryptLocalRelation
+import org.apache.spark.sql.catalyst.expressions.PromotePrecision
+import org.apache.spark.sql.catalyst.expressions.CheckOverflow
 
 object Utils extends Logging {
   private val perf: Boolean = System.getenv("SGX_PERF") == "1"
@@ -350,8 +351,6 @@ object Utils extends Logging {
     rdd.foreach(x => {})
   }
 
-
-
   def flatbuffersCreateField(
       builder: FlatBufferBuilder, value: Any, dataType: DataType, isNull: Boolean): Int = {
     (value, dataType) match {
@@ -403,6 +402,18 @@ object Utils extends Logging {
           tuix.FieldUnion.FloatField,
           tuix.FloatField.createFloatField(builder, 0),
           isNull)
+      case (x: Decimal, DecimalType()) =>
+        tuix.Field.createField(
+          builder,
+          tuix.FieldUnion.FloatField,
+          tuix.FloatField.createFloatField(builder, x.toFloat),
+          isNull)
+      case (null, DecimalType()) =>
+        tuix.Field.createField(
+          builder,
+          tuix.FieldUnion.FloatField,
+          tuix.FloatField.createFloatField(builder, 0),
+          isNull)
       case (x: Double, DoubleType) =>
         tuix.Field.createField(
           builder,
@@ -779,6 +790,18 @@ object Utils extends Logging {
     op(fromChildren, tree)
   }
 
+  def getColType(dataType: DataType) = {
+    dataType match {
+        case IntegerType => tuix.ColType.IntegerType
+        case LongType => tuix.ColType.LongType
+        case FloatType => tuix.ColType.FloatType
+        case DecimalType() => tuix.ColType.FloatType
+        case DoubleType => tuix.ColType.DoubleType
+        case StringType => tuix.ColType.StringType
+        case _ => throw new OpaqueException("Type not supported: " + dataType.toString())
+    }
+  }
+
   /** Serialize an Expression into a tuix.Expr. Returns the offset of the written tuix.Expr. */
   def flatbuffersSerializeExpression(
     builder: FlatBufferBuilder, expr: Expression, input: Seq[Attribute]): Int = {
@@ -811,14 +834,7 @@ object Utils extends Logging {
             tuix.Cast.createCast(
               builder,
               childOffset,
-              dataType match {
-                case IntegerType => tuix.ColType.IntegerType
-                case LongType => tuix.ColType.LongType
-                case FloatType => tuix.ColType.FloatType
-                case DoubleType => tuix.ColType.DoubleType
-                case StringType => tuix.ColType.StringType
-              }))
-
+              getColType(dataType)))
         // Arithmetic
         case (Add(left, right), Seq(leftOffset, rightOffset)) =>
           tuix.Expr.createExpr(
@@ -1087,6 +1103,17 @@ object Utils extends Logging {
             tuix.ExprUnion.ClosestPoint,
             tuix.ClosestPoint.createClosestPoint(
               builder, leftOffset, rightOffset))
+
+        case (PromotePrecision(child), Seq(childOffset)) =>
+          // TODO: Implement decimal serialization, followed by PromotePrecision
+          childOffset
+
+        case (CheckOverflow(child, dataType, _), Seq(childOffset)) =>
+          // TODO: Implement decimal serialization, followed by CheckOverflow
+          childOffset
+
+        case (_, Seq(childOffset)) =>
+          throw new OpaqueException("Expression not supported: " + expr.toString())
       }
     }
   }
diff --git a/src/test/scala/edu/berkeley/cs/rise/opaque/TPCHTests.scala b/src/test/scala/edu/berkeley/cs/rise/opaque/TPCHTests.scala
index c32eb8436b..ed8da375c5 100644
--- a/src/test/scala/edu/berkeley/cs/rise/opaque/TPCHTests.scala
+++ b/src/test/scala/edu/berkeley/cs/rise/opaque/TPCHTests.scala
@@ -104,8 +104,8 @@ trait TPCHTests extends OpaqueTestsBase { self =>
     tpch.query(19, securityLevel, spark.sqlContext, numPartitions).collect.toSet
   }
 
-  testAgainstSpark("TPC-H 20", ignore) { securityLevel =>
-    tpch.query(20, securityLevel, spark.sqlContext, numPartitions).collect
+  testAgainstSpark("TPC-H 20") { securityLevel =>
+    tpch.query(20, securityLevel, spark.sqlContext, numPartitions).collect.toSet
   }
 
   testAgainstSpark("TPC-H 21", ignore) { securityLevel =>