diff --git a/modules/kobalt-plugin-api/src/main/kotlin/com/beust/kobalt/archive/MetaArchive.kt b/modules/kobalt-plugin-api/src/main/kotlin/com/beust/kobalt/archive/MetaArchive.kt
index 69918dd4..539ce238 100644
--- a/modules/kobalt-plugin-api/src/main/kotlin/com/beust/kobalt/archive/MetaArchive.kt
+++ b/modules/kobalt-plugin-api/src/main/kotlin/com/beust/kobalt/archive/MetaArchive.kt
@@ -25,7 +25,7 @@ class MetaArchive(outputFile: File, val manifest: Manifest?) : Closeable {
     fun addFile(f: File, entryFile: File, path: String?) {
         val file = f.normalize()
         FileInputStream(file).use { inputStream ->
-            val actualPath = if (path != null) path + entryFile.path else entryFile.path
+            val actualPath = KFiles.fixSlashes(if (path != null) path + entryFile.path else entryFile.path)
             ZipArchiveEntry(actualPath).let { entry ->
                 maybeAddEntry(entry) {
                     addEntry(entry, inputStream)
diff --git a/src/test/kotlin/com/beust/kobalt/VerifyKobaltZipTest.kt b/src/test/kotlin/com/beust/kobalt/VerifyKobaltZipTest.kt
index c15e95d2..7966c8b5 100644
--- a/src/test/kotlin/com/beust/kobalt/VerifyKobaltZipTest.kt
+++ b/src/test/kotlin/com/beust/kobalt/VerifyKobaltZipTest.kt
@@ -3,6 +3,7 @@ package com.beust.kobalt
 import com.beust.kobalt.misc.KFiles
 import com.beust.kobalt.misc.kobaltLog
 import com.beust.kobalt.misc.warn
+import org.assertj.core.api.Assertions.assertThat
 import org.testng.annotations.Test
 import java.io.File
 import java.io.FileInputStream
@@ -38,6 +39,7 @@ class VerifyKobaltZipTest : KobaltTest() {
             val stream = JarInputStream(FileInputStream(zipFilePath))
             var entry = stream.nextEntry
             while (entry != null) {
+                assertThat(entry.name).doesNotContain("\\")
                 if (! entry.name.startsWith(root)) {
                     throw AssertionError("Entries in the zip file should be under the directory $root")
                 }