1 files changed, 4 insertions, 1 deletions

diff --git a/src/lib/libcrypto/bn/bn_word.c b/src/lib/libcrypto/bn/bn_word.c
index cd59baa2c4..988e0ca7b3 100644
--- a/src/lib/libcrypto/bn/bn_word.c
+++ b/src/lib/libcrypto/bn/bn_word.c
@@ -123,7 +123,10 @@ int BN_add_word(BIGNUM *a, BN_ULONG w)
         i=0;
         for (;;)
                 {
-                l=(a->d[i]+(BN_ULONG)w)&BN_MASK2;
+                if (i >= a->top)
+                        l=w;
+                else
+                        l=(a->d[i]+(BN_ULONG)w)&BN_MASK2;
                 a->d[i]=l;
                 if (w > l)
                         w=1;