diff --git a/src/jp2image.cpp b/src/jp2image.cpp
index c32e3e42..da2128a3 100644
--- a/src/jp2image.cpp
+++ b/src/jp2image.cpp
@@ -317,7 +317,7 @@ namespace Exiv2
                            std::cout << "Exiv2::Jp2Image::readMetadata: Xmp data found\n";
 #endif
 
-                            rawData.alloc(box.boxLength - (sizeof(box) + sizeof(uuid)));
+                            rawData.alloc(box.boxLength - (u_int32_t)(sizeof(box) + sizeof(uuid)));
                             bufRead = io_->read(rawData.pData_, rawData.size_);
                             if (io_->error()) throw Error(14);
                             if (bufRead != rawData.size_) throw Error(20);
diff --git a/src/value.hpp b/src/value.hpp
index 59a72f9f..c3eb459f 100644
--- a/src/value.hpp
+++ b/src/value.hpp
@@ -1550,7 +1550,8 @@ namespace Exiv2 {
     {
         value_.clear();
         long ts = TypeInfo::typeSize(typeId());
-        if (len % ts != 0) len = (len / ts) * ts;
+        if (ts != 0)
+            if (len % ts != 0) len = (len / ts) * ts;
         for (long i = 0; i < len; i += ts) {
             value_.push_back(getValue<T>(buf + i, byteOrder));
         }