diff --git a/.gitattributes b/.gitattributes
new file mode 100644
index 0000000..2efe7e9
--- /dev/null
+++ b/.gitattributes
@@ -0,0 +1,2 @@
+# Mark EPUB files as binary to prevent any text transformations
+*.epub binary
diff --git a/dreader/managers/document.py b/dreader/managers/document.py
index bcf66be..3c75067 100644
--- a/dreader/managers/document.py
+++ b/dreader/managers/document.py
@@ -70,6 +70,9 @@ class DocumentManager:
 
         except Exception as e:
             print(f"Error loading EPUB: {e}")
+            import traceback
+            print(f"Full traceback:")
+            traceback.print_exc()
             return False
 
     def load_html(self, html_string: str, title: str = "HTML Document",
diff --git a/tests/data/library-epub/pg5200-images-3.epub b/tests/data/library-epub/pg5200-images-3.epub
index 09cd378..8670db9 100644
Binary files a/tests/data/library-epub/pg5200-images-3.epub and b/tests/data/library-epub/pg5200-images-3.epub differ
diff --git a/tests/test_settings_overlay.py b/tests/test_settings_overlay.py
index d5e8023..9786f0f 100644
--- a/tests/test_settings_overlay.py
+++ b/tests/test_settings_overlay.py
@@ -48,6 +48,13 @@ class TestSettingsOverlay(unittest.TestCase):
 
         # Test if it's a valid ZIP
         if test_epub.exists():
+            # Check file magic bytes
+            with open(test_epub, 'rb') as f:
+                first_bytes = f.read(10)
+                print(f"First 10 bytes (hex): {first_bytes.hex()}")
+                print(f"First 10 bytes (ascii): {first_bytes[:4]}")
+                print(f"Is PK header: {first_bytes[:2] == b'PK'}")
+
             try:
                 with zipfile.ZipFile(test_epub, 'r') as zf:
                     print(f"Valid ZIP: True")