diff --git a/crypto3/libs/multiprecision/include/nil/crypto3/multiprecision/cpp_int_modular/misc.hpp b/crypto3/libs/multiprecision/include/nil/crypto3/multiprecision/cpp_int_modular/misc.hpp
index 938814bca6..05323460f1 100644
--- a/crypto3/libs/multiprecision/include/nil/crypto3/multiprecision/cpp_int_modular/misc.hpp
+++ b/crypto3/libs/multiprecision/include/nil/crypto3/multiprecision/cpp_int_modular/misc.hpp
@@ -148,6 +148,8 @@ namespace boost {
                             return i * cpp_int_modular_backend<Bits>::limb_bits + 
                                 boost::multiprecision::detail::find_msb(a.limbs()[i]);
                     } 
+                    if (a.limbs()[0] == 0)
+                        return 0;
                     return boost::multiprecision::detail::find_msb(a.limbs()[0]);
                 }