diff --git a/EPPlus/Utils/CompundDocument/CompoundDocumentFile.cs b/EPPlus/Utils/CompundDocument/CompoundDocumentFile.cs
index 16d8f228..3c594bee 100644
--- a/EPPlus/Utils/CompundDocument/CompoundDocumentFile.cs
+++ b/EPPlus/Utils/CompundDocument/CompoundDocumentFile.cs
@@ -114,10 +114,12 @@ public static bool IsCompoundDocument(FileInfo fi)
         {
             try
             {
-                var fs = fi.OpenRead();
-                var b = new byte[8];
-                fs.Read(b, 0, 8);
-                return IsCompoundDocument(b);
+                using (var fs = fi.OpenRead())
+                {
+                    var b = new byte[8];
+                    fs.Read(b, 0, 8);
+                    return IsCompoundDocument(b);
+                }
             }
             catch
             {