diff --git a/spark/src/main/resources/spark.yml b/spark/src/main/resources/spark.yml
index e398aa3a6..4f610ded7 100644
--- a/spark/src/main/resources/spark.yml
+++ b/spark/src/main/resources/spark.yml
@@ -32,3 +32,12 @@ scalar_functions:
       - args:
           - value: DECIMAL<P,S>
         return: i64
+  -
+    name: make_decimal
+    description:  >-
+      Return the Decimal value of an unscaled Long.
+      Note: this expression is internal and created only by the optimizer,
+    impls:
+      - args:
+          - value: i64
+        return: DECIMAL<P,S>
diff --git a/spark/src/main/scala/io/substrait/spark/SparkExtension.scala b/spark/src/main/scala/io/substrait/spark/SparkExtension.scala
index 0d6d84b71..d61a06d3e 100644
--- a/spark/src/main/scala/io/substrait/spark/SparkExtension.scala
+++ b/spark/src/main/scala/io/substrait/spark/SparkExtension.scala
@@ -26,8 +26,10 @@ import scala.collection.JavaConverters
 import scala.collection.JavaConverters.asScalaBufferConverter
 
 object SparkExtension {
+  final val uri = "/spark.yml"
+
   private val SparkImpls: SimpleExtension.ExtensionCollection =
-    SimpleExtension.load(Collections.singletonList("/spark.yml"))
+    SimpleExtension.load(Collections.singletonList(uri))
 
   private val EXTENSION_COLLECTION: SimpleExtension.ExtensionCollection =
     SimpleExtension.loadDefaults()
diff --git a/spark/src/main/scala/io/substrait/spark/expression/FunctionMappings.scala b/spark/src/main/scala/io/substrait/spark/expression/FunctionMappings.scala
index 4bcae8dd9..27eebfc67 100644
--- a/spark/src/main/scala/io/substrait/spark/expression/FunctionMappings.scala
+++ b/spark/src/main/scala/io/substrait/spark/expression/FunctionMappings.scala
@@ -58,6 +58,7 @@ class FunctionMappings {
     s[Year]("year"),
 
     // internal
+    s[MakeDecimal]("make_decimal"),
     s[UnscaledValue]("unscaled")
   )
 
diff --git a/spark/src/main/scala/io/substrait/spark/expression/ToSparkExpression.scala b/spark/src/main/scala/io/substrait/spark/expression/ToSparkExpression.scala
index e928689fa..2279d5496 100644
--- a/spark/src/main/scala/io/substrait/spark/expression/ToSparkExpression.scala
+++ b/spark/src/main/scala/io/substrait/spark/expression/ToSparkExpression.scala
@@ -16,10 +16,10 @@
  */
 package io.substrait.spark.expression
 
-import io.substrait.spark.{DefaultExpressionVisitor, HasOutputStack, ToSubstraitType}
+import io.substrait.spark.{DefaultExpressionVisitor, HasOutputStack, SparkExtension, ToSubstraitType}
 import io.substrait.spark.logical.ToLogicalPlan
-import org.apache.spark.sql.catalyst.expressions.{CaseWhen, Cast, Expression, In, Literal, NamedExpression, ScalarSubquery}
-import org.apache.spark.sql.types.{Decimal, NullType}
+import org.apache.spark.sql.catalyst.expressions.{CaseWhen, Cast, Expression, In, Literal, MakeDecimal, NamedExpression, ScalarSubquery}
+import org.apache.spark.sql.types.Decimal
 import org.apache.spark.unsafe.types.UTF8String
 import io.substrait.`type`.{StringTypeVisitor, Type}
 import io.substrait.{expression => exp}
@@ -131,23 +131,32 @@ class ToSparkExpression(
         arg.accept(expr.declaration(), i, this)
     }
 
-    scalarFunctionConverter
-      .getSparkExpressionFromSubstraitFunc(expr.declaration().key(), expr.outputType())
-      .flatMap(sig => Option(sig.makeCall(args)))
-      .getOrElse({
-        val msg = String.format(
-          "Unable to convert scalar function %s(%s).",
-          expr.declaration.name,
-          expr.arguments.asScala
-            .map {
-              case ea: exp.EnumArg => ea.value.toString
-              case e: SExpression => e.getType.accept(new StringTypeVisitor)
-              case t: Type => t.accept(new StringTypeVisitor)
-              case a => throw new IllegalStateException("Unexpected value: " + a)
-            }
-            .mkString(", ")
-        )
-        throw new IllegalArgumentException(msg)
-      })
+    expr.declaration.name match {
+      case "make_decimal" if expr.declaration.uri == SparkExtension.uri => expr.outputType match {
+        // Need special case handing of this internal function.
+        // Because the precision and scale arguments are extracted from the output type,
+        // we can't use the generic scalar function conversion mechanism here.
+        case d: Type.Decimal => MakeDecimal(args.head, d.precision, d.scale)
+        case _ => throw new IllegalArgumentException("Output type of MakeDecimal must be a decimal type")
+      }
+      case _ => scalarFunctionConverter
+        .getSparkExpressionFromSubstraitFunc(expr.declaration().key(), expr.outputType())
+        .flatMap(sig => Option(sig.makeCall(args)))
+        .getOrElse({
+          val msg = String.format(
+            "Unable to convert scalar function %s(%s).",
+            expr.declaration.name,
+            expr.arguments.asScala
+              .map {
+                case ea: exp.EnumArg => ea.value.toString
+                case e: SExpression => e.getType.accept(new StringTypeVisitor)
+                case t: Type => t.accept(new StringTypeVisitor)
+                case a => throw new IllegalStateException("Unexpected value: " + a)
+              }
+              .mkString(", ")
+          )
+          throw new IllegalArgumentException(msg)
+        })
+    }
   }
 }
diff --git a/spark/src/test/scala/io/substrait/spark/TPCDSPlan.scala b/spark/src/test/scala/io/substrait/spark/TPCDSPlan.scala
index fd35b551a..f880b25a4 100644
--- a/spark/src/test/scala/io/substrait/spark/TPCDSPlan.scala
+++ b/spark/src/test/scala/io/substrait/spark/TPCDSPlan.scala
@@ -32,7 +32,16 @@ class TPCDSPlan extends TPCDSBase with SubstraitPlanTestBase {
   }
 
   // "q9" failed in spark 3.3
-  val successfulSQL: Set[String] = Set("q4", "q7", "q18", "q22", "q26", "q28", "q29", "q37", "q41", "q48", "q50", "q62", "q69", "q82", "q85", "q88", "q90", "q93", "q96", "q97", "q99")
+  val successfulSQL: Set[String] = Set("q1", "q3", "q4", "q7",
+    "q11", "q13", "q15", "q16", "q18", "q19",
+    "q22", "q25", "q26", "q28", "q29",
+    "q30", "q31", "q32", "q37",
+    "q41", "q42", "q43", "q46", "q48",
+    "q50", "q52", "q55", "q58", "q59",
+    "q61", "q62", "q65", "q68", "q69",
+    "q79",
+    "q81", "q82", "q85", "q88",
+    "q90", "q91", "q92", "q93", "q94", "q95", "q96", "q97", "q99")
 
   tpcdsQueries.foreach {
     q =>