diff --git a/libXISF b/libXISF
index 9a32138..fa39440 160000
--- a/libXISF
+++ b/libXISF
@@ -1 +1 @@
-Subproject commit 9a32138f6aeb08cdb40f168e7b58e5e29fdfc73d
+Subproject commit fa39440b9e48dd42382d7b71db084f9560476537
diff --git a/src/rawimage.cpp b/src/rawimage.cpp
index 83d5671..c8cf346 100644
--- a/src/rawimage.cpp
+++ b/src/rawimage.cpp
@@ -403,9 +403,9 @@ uint32_t RawImage::norm() const
     }
 }
 
-uint32_t RawImage::widthBytes() const
+uint64_t RawImage::widthBytes() const
 {
-    return m_ch * m_width * typeSize(m_type);
+    return (uint64_t)m_ch * m_width * typeSize(m_type);
 }
 
 uint32_t RawImage::widthSamples() const
diff --git a/src/rawimage.h b/src/rawimage.h
index 50bc160..83fc70c 100644
--- a/src/rawimage.h
+++ b/src/rawimage.h
@@ -97,7 +97,7 @@ public:
     uint64_t size() const;
     DataType type() const;
     uint32_t norm() const;
-    uint32_t widthBytes() const;
+    uint64_t widthBytes() const;
     uint32_t widthSamples() const;
     void* data();
     const void* data() const;