c3-lang/libtommath

diff --git a/bn_mp_error_to_string.c b/bn_mp_error_to_string.c
index 59595eb..97b35ae 100644
--- a/bn_mp_error_to_string.c
+++ b/bn_mp_error_to_string.c
@@ -9,6 +9,8 @@ const char *mp_error_to_string(int code)
    switch (code) {
    case MP_OKAY:
       return "Successful";
+   case MP_ERR:
+      return "Unknown error";
    case MP_MEM:
       return "Out of heap";
    case MP_VAL: