diff --git a/contrib/api_template.py b/contrib/api_template.py
index 2ec34fa..7560372 100644
--- a/contrib/api_template.py
+++ b/contrib/api_template.py
@@ -97,6 +97,23 @@ class YourAPI:
                 The metadata as a dict
             """
 
+            # metadata types. have to be correct to be valid
+            {
+                "Title": str,
+                "Series": str,
+                "Number": str,
+                "Count": int,
+                "Volume": int,
+                "Summary": str,
+                "Genre": str,
+                "Web": str,
+                "PageCount": int,
+                "LanguageISO": str,
+                "Format": str,
+                "ScanInformation": str,
+                "SeriesGroup": str,
+            }
+
             # example
             return {
                 "Volume": "abc",
diff --git a/mangadlp/api/mangadex.py b/mangadlp/api/mangadex.py
index 4e35110..1ad23ce 100644
--- a/mangadlp/api/mangadex.py
+++ b/mangadlp/api/mangadex.py
@@ -163,12 +163,12 @@ class Mangadex:
             for chapter in r.json()["data"]:
                 attributes: dict = chapter["attributes"]
                 # chapter infos from feed
-                chapter_num = attributes.get("chapter") or ""
-                chapter_vol = attributes.get("volume") or ""
-                chapter_uuid = chapter.get("id") or ""
-                chapter_name = attributes.get("title") or ""
-                chapter_external = attributes.get("externalUrl") or ""
-                chapter_pages = attributes.get("pages") or ""
+                chapter_num: str = attributes.get("chapter") or ""
+                chapter_vol: str = attributes.get("volume") or ""
+                chapter_uuid: str = chapter.get("id") or ""
+                chapter_name: str = attributes.get("title") or ""
+                chapter_external: str = attributes.get("externalUrl") or ""
+                chapter_pages: int = attributes.get("pages") or 0
 
                 # check for chapter title and fix it
                 if chapter_name:
@@ -268,7 +268,7 @@ class Mangadex:
 
         chapter_data = self.manga_chapter_data[chapter]
         metadata = {
-            "Volume": chapter_data["volume"],
+            "Volume": int(chapter_data["volume"]),
             "Number": chapter_data["chapter"],
             "PageCount": chapter_data["pages"],
             "Title": chapter_data["name"],
diff --git a/mangadlp/metadata.py b/mangadlp/metadata.py
index 7b3f97f..aa49234 100644
--- a/mangadlp/metadata.py
+++ b/mangadlp/metadata.py
@@ -9,6 +9,23 @@ def write_metadata(chapter_path: Path, metadata: dict) -> None:
         log.warning("Can't add metadata for pdf format. Skipping")
         return
 
+    # define metadata types
+    metadata_types: dict[str, type] = {
+        "Title": str,
+        "Series": str,
+        "Number": str,
+        "Count": int,
+        "Volume": int,
+        "Summary": str,
+        "Genre": str,
+        "Web": str,
+        "PageCount": int,
+        "LanguageISO": str,
+        "Format": str,
+        "ScanInformation": str,
+        "SeriesGroup": str,
+    }
+
     try:
         metadata_template = Path("mangadlp/metadata/ComicInfo.xml").read_text(
             encoding="utf8"
@@ -22,12 +39,22 @@ def write_metadata(chapter_path: Path, metadata: dict) -> None:
     log.info(f"Writing metadata to: '{metadata_file}'")
     log.debug(f"Metadata items: {metadata}")
     for key, value in metadata.items():
+        # check if metadata is empty
         if not value:
             continue
+        # try to match with template
         try:
             metadata_empty["ComicInfo"][key]
         except KeyError:
             continue
+        # check if metadata type is correct
+        log.debug(f"Key:{key} -> value={type(value)} -> check={metadata_types[key]}")
+        if not isinstance(value, metadata_types[key]):  # noqa
+            log.warning(
+                f"Metadata has wrong type: {key}:{metadata_types[key]} -> {value}"
+            )
+            continue
+
         log.debug(f"Updating metadata: '{key}' = '{value}'")
         metadata_empty["ComicInfo"][key] = value
 
diff --git a/mangadlp/metadata/ComicInfo.xml b/mangadlp/metadata/ComicInfo.xml
index 0bc92af..5472a58 100644
--- a/mangadlp/metadata/ComicInfo.xml
+++ b/mangadlp/metadata/ComicInfo.xml
@@ -14,7 +14,7 @@
     <ScanInformation></ScanInformation>
     <SeriesGroup></SeriesGroup>
     <BlackAndWhite>Unknown</BlackAndWhite>
-    <Manga>Yes</Manga>
     <AgeRating>Unknown</AgeRating>
+    <Manga>Yes</Manga>
     <Notes>Downloaded with https://github.com/olofvndrhr/manga-dlp</Notes>
 </ComicInfo>