2 files changed, 11 insertions, 3 deletions
diff --git a/src/lib/math/numbertheory/monty.cpp b/src/lib/math/numbertheory/monty.cpp
index 33d15de5b..1cdc7fa9a 100644
--- a/src/lib/math/numbertheory/monty.cpp
+++ b/src/lib/math/numbertheory/monty.cpp
@@ -281,8 +281,13 @@ Montgomery_Int Montgomery_Int::operator-(const Montgomery_Int& other) const
 
 Montgomery_Int& Montgomery_Int::operator+=(const Montgomery_Int& other)
    {
-   m_v += other.m_v;
    secure_vector<word> ws;
+   return this->add(other, ws);
+   }
+
+Montgomery_Int& Montgomery_Int::add(const Montgomery_Int& other, secure_vector<word>& ws)
+   {
+   m_v += other.m_v;
    m_v.reduce_below(m_params->p(), ws);
    return (*this);
    }
diff --git a/src/lib/math/numbertheory/monty.h b/src/lib/math/numbertheory/monty.h
index 2af655230..8a594325c 100644
--- a/src/lib/math/numbertheory/monty.h
+++ b/src/lib/math/numbertheory/monty.h
@@ -18,7 +18,7 @@ class Montgomery_Params;
 /**
 * The Montgomery representation of an integer
 */
-class Montgomery_Int final
+class BOTAN_UNSTABLE_API Montgomery_Int final
    {
    public:
       /**
@@ -75,6 +75,9 @@ class Montgomery_Int final
 
       Montgomery_Int& operator*=(const secure_vector<word>& other);
 
+      Montgomery_Int& add(const Montgomery_Int& other,
+                          secure_vector<word>& ws);
+
       Montgomery_Int mul(const Montgomery_Int& other,
                          secure_vector<word>& ws) const;
 
@@ -111,7 +114,7 @@ class Montgomery_Int final
 /**
 * Parameters for Montgomery Reduction
 */
-class Montgomery_Params final
+class BOTAN_UNSTABLE_API Montgomery_Params final
    {
    public:
       /**