diff --git a/src/main/java/com/dostalgia/UploadResource.java b/src/main/java/com/dostalgia/UploadResource.java
index b489729..798f858 100644
--- a/src/main/java/com/dostalgia/UploadResource.java
+++ b/src/main/java/com/dostalgia/UploadResource.java
@@ -88,7 +88,7 @@ public class UploadResource {
                 // Write dosbox.conf (full config, not just autoexec)
                 Path jsdos = gameDir.resolve(".jsdos");
                 Files.createDirectories(jsdos);
-                String relExe = extractDir.relativize(Path.of(mainExe)).toString().replace('\\', '/');
+                String relExe = extractDir.relativize(Path.of(mainExe)).toString().replace('/', '\\');
                 String conf = buildDosboxConf(relExe);
                 Files.writeString(jsdos.resolve("dosbox.conf"), conf);
                 Files.write(jsdos.resolve("jsdos.json"), buildJsdosJson(relExe));
@@ -216,7 +216,7 @@ public class UploadResource {
             // Create .jsdos config (full config, not just autoexec)
             Path jsdos = tmpBundle.resolve(".jsdos");
             Files.createDirectories(jsdos);
-            String relExe = extractDir.relativize(Path.of(mainExe)).toString().replace('\\', '/');
+            String relExe = extractDir.relativize(Path.of(mainExe)).toString().replace('/', '\\');
             String conf = buildDosboxConf(relExe);
             Files.writeString(jsdos.resolve("dosbox.conf"), conf);
             Files.write(jsdos.resolve("jsdos.json"), buildJsdosJson(relExe));
@@ -274,7 +274,7 @@ public class UploadResource {
         // Split into directory and executable components for subdirectory support
         String dir = "";
         String exe = relExe;
-        int idx = relExe.lastIndexOf('/');
+        int idx = Math.max(relExe.lastIndexOf('/'), relExe.lastIndexOf('\\'));
         if (idx >= 0) {
             dir = relExe.substring(0, idx);
             exe = relExe.substring(idx + 1);