diff --git a/src/matchers/doc.rs b/src/matchers/doc.rs
index 71c3a03..ee64ac7 100644
--- a/src/matchers/doc.rs
+++ b/src/matchers/doc.rs
@@ -84,7 +84,6 @@ fn msooxml(buf: &[u8]) -> Option<DocType> {
     // file we have.  Correct the mimetype with the registered ones:
     // http://technet.microsoft.com/en-us/library/cc179224.aspx
     start_offset += idx + 4 + 26;
-    check_msooml(buf, start_offset)?;
 
     // OpenOffice/Libreoffice orders ZIP entry differently, so check the 4th file
     start_offset += 26;
@@ -94,6 +93,13 @@ fn msooxml(buf: &[u8]) -> Option<DocType> {
         None => return Some(DocType::OOXML),
     };
 
+    // Check the 5th file, for Numbers and Apache POI sources
+    let idx = search(buf, start_offset, 6000);
+    match idx {
+        Some(idx) => start_offset += idx + 4 + 26,
+        None => return Some(DocType::OOXML),
+    };
+
     let typo = check_msooml(buf, start_offset);
     if typo.is_some() {
         return typo;