diff --git a/integer.cpp b/integer.cpp
index bcb2a734..e89aee5e 100644
--- a/integer.cpp
+++ b/integer.cpp
@@ -4362,12 +4362,18 @@ Integer Integer::MultiplicativeInverse() const
 Integer a_times_b_mod_c(const Integer &x, const Integer& y, const Integer& m)
 {
 	CRYPTOPP_ASSERT(m != 0);
+	if (m == 0)
+		throw Integer::DivideByZero();
+
 	return x*y%m;
 }
 
 Integer a_exp_b_mod_c(const Integer &x, const Integer& e, const Integer& m)
 {
 	CRYPTOPP_ASSERT(m != 0);
+	if (m == 0)
+		throw Integer::DivideByZero();
+
 	ModularArithmetic mr(m);
 	return mr.Exponentiate(x, e);
 }