diff --git a/src/ndb.rs b/src/ndb.rs
index 8294af8..fa04f1f 100644
--- a/src/ndb.rs
+++ b/src/ndb.rs
@@ -448,4 +448,35 @@ mod tests {
             assert_eq!(note.kind(), 1);
         }
     }
+
+    #[test]
+    #[cfg(target_os = "windows")]
+    fn test_windows_large_mapsize() {
+        use std::{fs, path::Path};
+
+        let db = "target/testdbs/event_works";
+        test_util::cleanup_db(&db);
+
+        {
+            // 32 TiB should be way too big for CI
+            let config = Config::new().set_mapsize(1024usize * 1024usize * 1024usize * 1024usize * 32usize);
+            let ndb = Ndb::new(db, &config);
+            assert!(ndb.is_ok());
+        }
+
+        let file_len = fs::metadata(Path::new(db).join("data.mdb"))
+            .expect("metadata")
+            .len();
+
+        assert!(file_len > 0);
+
+        if cfg!(target_os = "windows") {
+            assert_ne!(file_len, 1048576);
+        } else {
+            assert!(file_len < 1024u64 * 1024u64);
+        }
+
+        // If the file size is the default mapsize on windows, this is a bug!
+
+    }
 }