diff --git a/src/test/kotlin/com/beust/kobalt/VerifyKobaltZip.kt b/src/test/kotlin/com/beust/kobalt/VerifyKobaltZip.kt
index fa209399..9f93b30c 100644
--- a/src/test/kotlin/com/beust/kobalt/VerifyKobaltZip.kt
+++ b/src/test/kotlin/com/beust/kobalt/VerifyKobaltZip.kt
@@ -4,11 +4,18 @@ import com.beust.kobalt.api.Kobalt
 import com.beust.kobalt.misc.KFiles
 import com.beust.kobalt.misc.log
 import org.testng.annotations.Test
+import java.io.File
 import java.io.FileInputStream
+import java.io.InputStream
 import java.util.jar.JarFile
 import java.util.jar.JarInputStream
 
 class VerifyKobaltZipTest : KobaltTest() {
+    @Test
+    fun verifySourceJarFile() {
+        assertExistsInJar("kobalt-" + Kobalt.version + "-sources.jar", "com/beust/kobalt/Main.kt")
+    }
+
     @Test
     fun verifyZipFile() {
         var success = true
@@ -16,7 +23,7 @@ class VerifyKobaltZipTest : KobaltTest() {
         var foundJar = false
         var foundWrapperJar = false
 
-        val jarFilePath = "kobalt-" + Kobalt.version + ".jar"
+        val mainJarFilePath = "kobalt-" + Kobalt.version + ".jar"
         val zipFilePath = KFiles.joinDir("kobaltBuild", "libs", "kobalt-" + Kobalt.version + ".zip")
         val zipFile = JarFile(zipFilePath)
         val stream = JarInputStream(FileInputStream(zipFilePath))
@@ -24,11 +31,12 @@ class VerifyKobaltZipTest : KobaltTest() {
         while (entry != null) {
             if (entry.name == "kobaltw") {
                 foundKobaltw = true
-            } else if (entry.name.endsWith(jarFilePath)) {
+            } else if (entry.name.endsWith(mainJarFilePath)) {
                 val ins = zipFile.getInputStream(entry)
                 if (ins.available() < 20000000) {
-                    throw KobaltException(jarFilePath + " is too small: " + jarFilePath)
+                    throw KobaltException(mainJarFilePath + " is too small: " + mainJarFilePath)
                 }
+                verifyMainJarFile(ins)
                 foundJar = true
             } else if (entry.name.endsWith("kobalt-wrapper.jar")) {
                 foundWrapperJar = true
@@ -51,4 +59,25 @@ class VerifyKobaltZipTest : KobaltTest() {
         }
         log(1, "$zipFilePath looks correct")
     }
+
+    private fun assertExistsInJar(jarName: String, fileName: String) {
+        val sourceJarPath = KFiles.joinDir("kobaltBuild", "libs", jarName)
+        assertExistsInJar(JarInputStream(FileInputStream(File(sourceJarPath))), fileName)
+    }
+
+    private fun assertExistsInJar(stream: JarInputStream, fileName: String) {
+        var entry = stream.nextEntry
+        var found = false
+        while (entry != null) {
+            if (entry.name == fileName) found = true
+            entry = stream.nextEntry
+        }
+        if (! found) {
+            throw AssertionError("Couldn't find Main.kt in $fileName")
+        }
+    }
+
+    private fun verifyMainJarFile(ins: InputStream) {
+        assertExistsInJar(JarInputStream(ins), "com/beust/kobalt/MainKt.class")
+    }
 }