diff --git a/branches/tor-0_0_6-patches/src/common/crypto.c b/branches/tor-0_0_6-patches/src/common/crypto.c
index 5304180e32..76c96a9a3e 100644
--- a/branches/tor-0_0_6-patches/src/common/crypto.c
+++ b/branches/tor-0_0_6-patches/src/common/crypto.c
@@ -1018,9 +1018,12 @@ void crypto_digest_get_digest(crypto_digest_env_t *digest,
                               char *out, size_t out_len)
 {
   static char r[DIGEST_LEN];
+  SHA_CTX tmpctx;
   tor_assert(digest && out);
   tor_assert(out_len <= DIGEST_LEN);
-  SHA1_Final(r, &digest->d);
+  /* memcpy into a temporary ctx, since SHA1_Final clears the context */
+  memcpy(&tmpctx, &digest->d, sizeof(SHA_CTX));
+  SHA1_Final(r, &tmpctx);
   memcpy(out, r, out_len);
 }