diff --git a/tools/analyse.cpp b/tools/analyse.cpp
index a83a660..051434a 100644
--- a/tools/analyse.cpp
+++ b/tools/analyse.cpp
@@ -236,7 +236,7 @@ int main (int argc, char const **argv)
     auto const unique_bytes = std::accumulate (
         src.begin (),
         src.end   (),
-        0, [] (auto const &accum, auto const &rhs) { return accum + rhs.size (); }
+        std::uintmax_t {0}, [] (auto const &accum, auto const &rhs) { return accum + rhs.size (); }
     );
 
     auto const duplicated_bytes = total_bytes - unique_bytes;