diff --git a/source/detail/vector_streambuf.hpp b/source/detail/vector_streambuf.hpp
index f7840032..8189cebd 100644
--- a/source/detail/vector_streambuf.hpp
+++ b/source/detail/vector_streambuf.hpp
@@ -153,7 +153,7 @@ private:
         else
         {
             auto position_size = data_.size();
-            auto required_size = static_cast<std::size_t>(position_ + n);
+            auto required_size = static_cast<std::size_t>(position_ + static_cast<std::streampos>(n));
             data_.resize(std::max(position_size, required_size));
         }
 
diff --git a/source/workbook/tests/test_consume_xlsx.hpp b/source/workbook/tests/test_consume_xlsx.hpp
index 4f388e69..4844e3cd 100644
--- a/source/workbook/tests/test_consume_xlsx.hpp
+++ b/source/workbook/tests/test_consume_xlsx.hpp
@@ -7,7 +7,7 @@
 #include <helpers/path_helper.hpp>
 #include <xlnt/workbook/workbook.hpp>
 
-#define TEST_CRYPTO false
+#define TEST_CRYPTO true
 
 #ifndef TEST_CRYPTO
 #define TEST_CRYPTO false
diff --git a/tests/helpers/xml_helper.hpp b/tests/helpers/xml_helper.hpp
index 6538569d..d6632de3 100644
--- a/tests/helpers/xml_helper.hpp
+++ b/tests/helpers/xml_helper.hpp
@@ -302,18 +302,20 @@ public:
 		delete stream;
 		return compare_files(expected, contents, content_type);
 	}
-
-	static bool file_matches_archive_member(const xlnt::path &file,
+    
+    static bool file_matches_archive_member(const xlnt::path &file,
 		Partio::ZipFileReader &archive,
 		const xlnt::path &member,
         const std::string &content_type)
 	{
 		if (!archive.Has_File(member.string())) return false;
-		std::ostringstream member_stream;
-		auto stream = archive.Get_File(member.string(), true);
-		std::string contents((std::istreambuf_iterator<char>(*stream)), (std::istreambuf_iterator<char>()));
-		delete stream;
-		auto result = compare_files(file.read_contents(), contents, content_type);
+		std::vector<std::uint8_t> member_data;
+		xlnt::detail::vector_ostreambuf member_data_buffer(member_data);
+		std::ostream member_data_stream(&member_data_buffer);
+		std::unique_ptr<std::istream> member_stream(archive.Get_File(member.string(), true));
+		member_data_stream << member_stream->rdbuf();
+		std::string contents(member_data.begin(), member_data.end());
+		return compare_files(file.read_contents(), contents, content_type);
 	}
 
 	static bool file_matches_document(const xlnt::path &expected,