diff --git a/math/vecops/inc/ROOT/RAdoptAllocator.hxx b/math/vecops/inc/ROOT/RAdoptAllocator.hxx
index 9750a523f1ef2..fe6e8b5c634ea 100644
--- a/math/vecops/inc/ROOT/RAdoptAllocator.hxx
+++ b/math/vecops/inc/ROOT/RAdoptAllocator.hxx
@@ -136,6 +136,8 @@ public:
    }
 
    bool operator!=(const RAdoptAllocator<T> &other) { return !(*this == other); }
+
+   size_type max_size() const { return fStdAllocator.max_size(); };
 };
 
 // The different semantics of std::vector<bool> make  memory adoption through a