diff --git a/src/Makefile.am b/src/Makefile.am
index 4d76176f3..25038c1ee 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -47,7 +47,7 @@ $(LIBSECP256K1): $(wildcard secp256k1/src/*) $(wildcard secp256k1/include/*)
 -include collate-libsnark
 collate-libsnark: $(LIBSNARK)
 
-LIBSNARK_CXXFLAGS = -fPIC -DBINARY_OUTPUT -DNO_PT_COMPRESSION=1
+LIBSNARK_CXXFLAGS = -fPIC -DBINARY_OUTPUT -DNO_PT_COMPRESSION=1 -fstack-protector-all
 LIBSNARK_CONFIG_FLAGS = CURVE=ALT_BN128 NO_PROCPS=1 NO_DOCS=1 STATIC=1 NO_SUPERCOP=1 FEATUREFLAGS=-DMONTGOMERY_OUTPUT NO_COPY_DEPINST=1 NO_COMPILE_LIBGTEST=1
 if HAVE_OPENMP
 LIBSNARK_CONFIG_FLAGS += MULTICORE=1
diff --git a/src/snark/src/algebra/fields/bigint.tcc b/src/snark/src/algebra/fields/bigint.tcc
index f81addf45..c1777ad46 100644
--- a/src/snark/src/algebra/fields/bigint.tcc
+++ b/src/snark/src/algebra/fields/bigint.tcc
@@ -201,7 +201,7 @@ inline bigint<m> bigint<n>::shorten(const bigint<m>& q, const char *msg) const
         }
     }
     bigint<m> res;
-    mpn_copyi(res.data, data, n);
+    mpn_copyi(res.data, data, m);
     res.limit(q, msg);
     return res;
 }