diff --git a/src/zip.rs b/src/zip.rs
index 247840a..722644e 100644
--- a/src/zip.rs
+++ b/src/zip.rs
@@ -129,8 +129,14 @@ impl UploadedFile {
 
     fn central_directory_header(&self, local_header_offset: usize, hash: u32) -> Vec<u8> {
         let mut header = vec![
-            0x50, 0x4b, 0x01, 0x02, // Central directory file header signature
-            45, 3,                  // Made by a Unix system supporting version 4.5
+            // Central directory file header signature
+            0x50, 0x4b, 0x01, 0x02,
+            // Made by a "DOS" system supporting version 4.5 - if we
+            // say it's made by a Unix system, then unzip will expect
+            // it to have embedded Unix permission information, and
+            // will set all the files to mode 000 when that's not
+            // present :/
+            45, 0,
         ];
         header.append(&mut self.shared_header_fields(Some(hash)));
         header.append(&mut vec![
@@ -165,7 +171,7 @@ fn end_of_central_directory(files: &[UploadedFile]) -> Vec<u8> {
     ];
     append_0(&mut eocd, 7); // pad out the rest of the size field
     eocd.append(&mut vec![
-        45, 3, // Made by a Unix system supporting version 4.5
+        45, 0, // Made by a "DOS" system supporting version 4.5, see above
         45, 0, // Minimum version 4.5 to extract
     ]);
     append_0(&mut eocd, 8); // Two 4-byte disk numbers, both 0