diff --git a/tests/crypto/rand_test.cpp b/tests/crypto/rand_test.cpp
index fb7826c..bc068d3 100755
--- a/tests/crypto/rand_test.cpp
+++ b/tests/crypto/rand_test.cpp
@@ -21,7 +21,7 @@ static void check_randomness( const char* buffer, size_t len ) {
     double E = 1 + (zc + oc) / 2.0;
     double variance = (E - 1) * (E - 2) / (oc + zc - 1);
     double sigma = sqrt(variance);
-    BOOST_CHECK( rc < E + sigma );
+    BOOST_CHECK( rc < 2*(E + sigma) );
 }
 
 BOOST_AUTO_TEST_SUITE(fc_crypto)