diff --git a/API/Services/Plus/ExternalMetadataService.cs b/API/Services/Plus/ExternalMetadataService.cs
index bdbff2105..750dc723e 100644
--- a/API/Services/Plus/ExternalMetadataService.cs
+++ b/API/Services/Plus/ExternalMetadataService.cs
@@ -1582,16 +1582,16 @@ public class ExternalMetadataService : IExternalMetadataService
             var maxVolume = (int)(nonSpecialVolumes.Count != 0 ? nonSpecialVolumes.Max(v => v.MaxNumber) : 0);
             var maxChapter = (int)chapters.Max(c => c.MaxNumber);
 
-            if (series.Format == MangaFormat.Epub || series.Format == MangaFormat.Pdf && chapters.Count == 1)
+            if (series.Format is MangaFormat.Epub or MangaFormat.Pdf && chapters.Count == 1)
             {
                 series.Metadata.MaxCount = 1;
             }
-            else if (series.Metadata.TotalCount <= 1 && chapters.Count == 1 && chapters[0].IsSpecial)
+            else if (series.Metadata.TotalCount <= 1 && chapters is [{ IsSpecial: true }])
             {
                 series.Metadata.MaxCount = series.Metadata.TotalCount;
             }
             else if ((maxChapter == Parser.DefaultChapterNumber || maxChapter > series.Metadata.TotalCount) &&
-                     maxVolume <= series.Metadata.TotalCount)
+                     maxVolume <= series.Metadata.TotalCount && maxVolume != Parser.DefaultChapterNumber)
             {
                 series.Metadata.MaxCount = maxVolume;
             }
@@ -1612,8 +1612,7 @@ public class ExternalMetadataService : IExternalMetadataService
             {
                 status = PublicationStatus.Ended;
 
-                // Check if all volumes/chapters match the total count
-                if (series.Metadata.MaxCount == series.Metadata.TotalCount && series.Metadata.TotalCount > 0)
+                if (IsSeriesCompleted(series, chapters, externalMetadata, maxVolume, maxChapter))
                 {
                     status = PublicationStatus.Completed;
                 }
@@ -1629,6 +1628,56 @@ public class ExternalMetadataService : IExternalMetadataService
         return PublicationStatus.OnGoing;
     }
 
+    /// <summary>
+    /// Returns true if the series should be marked as completed, checks loosy with #chapters and #series; Also tries
+    /// to use specials to reach the required amount
+    /// </summary>
+    /// <param name="series"></param>
+    /// <param name="chapters"></param>
+    /// <param name="externalMetadata"></param>
+    /// <param name="maxVolumes"></param>
+    /// <param name="maxChapters"></param>
+    /// <returns></returns>
+    /// <remarks>Updates MaxCount and TotalCount if a loosy check is used to set as completed</remarks>
+    private static bool IsSeriesCompleted(Series series, List<Chapter> chapters, ExternalSeriesDetailDto externalMetadata, int maxVolumes, int maxChapters)
+    {
+        // A series is completed if exactly the amount is found
+        if (series.Metadata.MaxCount == series.Metadata.TotalCount && series.Metadata.TotalCount > 0)
+        {
+            return true;
+        }
+
+        // If volumes are collected, check if we reach the required volumes by including specials
+        //
+        // TODO BUG: If the series has specials, that are not included in the external count. But you do own them
+        //           This may mark the series as completed pre-maturely
+        if (maxVolumes != Parser.DefaultChapterNumber && series.Volumes.Count == externalMetadata.Volumes)
+        {
+            series.Metadata.MaxCount = series.Volumes.Count;
+            series.Metadata.TotalCount = series.Volumes.Count;
+            return true;
+        }
+
+        // If no volumes are collected, the series is completed if we reach or exceed the external chapters
+        if (maxVolumes == Parser.DefaultChapterNumber && series.Metadata.MaxCount >= externalMetadata.Chapters)
+        {
+            series.Metadata.TotalCount = series.Metadata.MaxCount;
+            return true;
+        }
+
+        // If no volumes are collected, the series is complete if we reach or exceed the external chapters while including
+        // prologues, and extra chapters
+        if (maxVolumes == Parser.DefaultChapterNumber && chapters.Count >= externalMetadata.Chapters)
+        {
+            series.Metadata.TotalCount = chapters.Count;
+            series.Metadata.MaxCount = chapters.Count;
+            return true;
+        }
+
+
+        return false;
+    }
+
     private static Dictionary<MetadataFieldType, List<string>> ApplyFieldMappings(IEnumerable<string> values, MetadataFieldType sourceType, List<MetadataFieldMappingDto> mappings)
     {
         var result = new Dictionary<MetadataFieldType, List<string>>();