diff --git a/build.sbt b/build.sbt
index 1cda078284d..ac313e05c64 100644
--- a/build.sbt
+++ b/build.sbt
@@ -322,20 +322,35 @@ val icebergSparkRuntimeArtifactName = {
 }
 
 lazy val testDeltaIcebergJar = (project in file("testDeltaIcebergJar"))
+  // delta-iceberg depends on delta-spark! So, we need to include it during our test.
+  .dependsOn(spark % "test")
   .settings(
     name := "test-delta-iceberg-jar",
     commonSettings,
     skipReleaseSettings,
+    exportJars := true,
     Compile / unmanagedJars += (iceberg / assembly).value,
     libraryDependencies ++= Seq(
       "org.apache.hadoop" % "hadoop-client" % hadoopVersion,
       "org.scalatest" %% "scalatest" % scalaTestVersion % "test",
-      "org.apache.spark" %% "spark-core" % sparkVersion
+      "org.apache.spark" %% "spark-core" % sparkVersion % "test"
     )
   )
 
+val deltaIcebergSparkIncludePrefixes = Seq(
+  // We want everything from this package
+  "org/apache/spark/sql/delta/icebergShaded",
+
+  // We only want the files in this project from this package. e.g. we want to exclude
+  // org/apache/spark/sql/delta/commands/convert/ConvertTargetFile.class (from delta-spark project).
+  "org/apache/spark/sql/delta/commands/convert/IcebergFileManifest",
+  "org/apache/spark/sql/delta/commands/convert/IcebergSchemaUtils",
+  "org/apache/spark/sql/delta/commands/convert/IcebergTable"
+)
+
 // Build using: build/sbt clean icebergShaded/compile iceberg/compile
 // It will fail the first time, just re-run it.
+// scalastyle:off println
 lazy val iceberg = (project in file("iceberg"))
   .dependsOn(spark % "compile->compile;test->test;provided->provided")
   .settings (
@@ -358,7 +373,7 @@ lazy val iceberg = (project in file("iceberg"))
     assembly / test := {},
     assembly / assemblyExcludedJars := {
       // Note: the input here is only `libraryDependencies` jars, not `.dependsOn(_)` jars.
-      val includes = Seq(
+      val allowedJars = Seq(
         "iceberg-shaded_2.12-3.0.0-SNAPSHOT.jar",
         "scala-library-2.12.15.jar",
         "scala-collection-compat_2.12-2.1.1.jar",
@@ -372,10 +387,8 @@ lazy val iceberg = (project in file("iceberg"))
 
       // Return `true` when we want the jar `f` to be excluded from the assembly jar
       cp.filter { f =>
-        val doExclude = !includes.contains(f.data.getName)
-        // scalastyle:off println
-        println(s"${f.data.getName} :: exclude? $doExclude")
-        // scalastyle:on println
+        val doExclude = !allowedJars.contains(f.data.getName)
+        println(s"Excluding jar: ${f.data.getName} ? $doExclude")
         doExclude
       }
     },
@@ -387,22 +400,24 @@ lazy val iceberg = (project in file("iceberg"))
         // - delta-storage will bring in classes: io/delta/storage
         // - delta-spark will bring in classes: io/delta/exceptions/, io/delta/implicits,
         //   io/delta/package, io/delta/sql, io/delta/tables,
-        println(s"BBBB io/delta/$xs")
+        println(s"Discarding class: io/delta/${xs.mkString("/")}")
+        MergeStrategy.discard
+      case PathList("com", "databricks", xs @ _*) =>
+        // delta-spark will bring in com/databricks/spark/util
+        println(s"Discarding class: com/databricks/${xs.mkString("/")}")
         MergeStrategy.discard
-      case PathList("org", "apache", "spark", xs @ _*) =>
-        val includes = Seq("sql/delta/icebergShaded", "org.apache.spark.sql.delta.commands.convert")
-        val includes = Set(
-          List("sql", "delta", "icebergShaded"),
-          List("sql", "delta", "commands", "convert")
-        )
-        println(s"------> ${xs.mkString("/")}")
+      case PathList("org", "apache", "spark", xs @ _*)
+        if !deltaIcebergSparkIncludePrefixes.exists { prefix =>
+          s"org/apache/spark/${xs.mkString("/")}".startsWith(prefix) } =>
+        println(s"Discarding class: org/apache/spark/${xs.mkString("/")}")
         MergeStrategy.discard
       case x =>
-        println(s"AAAA $x")
+        println(s"Including class: $x")
         (assembly / assemblyMergeStrategy).value(x)
     },
     assemblyPackageScala / assembleArtifact := false
   )
+// scalastyle:on println
 
 lazy val generateIcebergJarsTask = TaskKey[Unit]("generateIcebergJars", "Generate Iceberg JARs")
 
diff --git a/testDeltaIcebergJar/src/test/scala/JarSuite.scala b/testDeltaIcebergJar/src/test/scala/JarSuite.scala
index 9069cd4a223..2f8dced74dc 100644
--- a/testDeltaIcebergJar/src/test/scala/JarSuite.scala
+++ b/testDeltaIcebergJar/src/test/scala/JarSuite.scala
@@ -25,23 +25,53 @@ import scala.collection.JavaConverters._
 import org.scalatest.funsuite.AnyFunSuite
 
 class JarSuite extends AnyFunSuite {
+
+  val allowedClassPrefixes = Seq(
+    // e.g. shadedForDelta/org/apache/iceberg/BaseTable.class
+    "shadedForDelta/",
+    // e.g. scala/collection/compat/immutable/ArraySeq.class
+    // e.g. scala/jdk/CollectionConverters.class
+    "scala/",
+    // e.g. org/apache/spark/sql/delta/icebergShaded/IcebergTransactionUtils.class
+    "org/apache/spark/sql/delta/icebergShaded/",
+    // We explicitly include all the /delta/commands/convert classes we want, to ensure we don't
+    // accidentally pull in some from delta-spark package.
+    "org/apache/spark/sql/delta/commands/convert/IcebergFileManifest",
+    "org/apache/spark/sql/delta/commands/convert/IcebergSchemaUtils",
+    "org/apache/spark/sql/delta/commands/convert/IcebergTable",
+    // e.g. org/apache/iceberg/transforms/IcebergPartitionUtil.class
+    "org/apache/iceberg/",
+    "com/github/benmanes/caffeine/"
+  )
+
   test("audit files in assembly jar") {
     // Step 1: load the jar (and make sure it exists)
     // scalastyle:off classforname
     val classUrl = Class.forName("org.apache.spark.sql.delta.icebergShaded.IcebergConverter").getResource("IcebergConverter.class")
     // scalastyle:on classforname
     assert(classUrl != null, "Could not find delta-iceberg jar")
-    println(classUrl)
     val connection = classUrl.openConnection().asInstanceOf[JarURLConnection]
-
-    val url = connection.getJarFileURL()
+    val url = connection.getJarFileURL
     val jarFile = new JarFile(new File(url.toURI))
 
-    // Step 2: Verify the JAR has the classes we want it to ahve
+    // Step 2: Verify the JAR has the classes we want it to have
     try {
-      val set = jarFile.entries().asScala.filter(!_.isDirectory).map(_.toString).toSet
-      println(set.toList.sorted.mkString("\n"))
+      val jarClasses = jarFile
+        .entries()
+        .asScala
+        .filter(!_.isDirectory)
+        .map(_.toString)
+        .filter(_.endsWith(".class")) // let's ignore any .properties or META-INF files for now
+        .toSet
+
+      val prohibitedJarClasses = jarClasses
+        .filter { clazz => !allowedClassPrefixes.exists(prefix => clazz.startsWith(prefix)) }
 
+      if (prohibitedJarClasses.nonEmpty) {
+        throw new Exception(
+            s"Prohibited jar class(es) found:\n- ${prohibitedJarClasses.mkString("\n- ")}"
+          )
+      }
     } finally {
       jarFile.close()
     }