diff --git a/tests/common/database_fixture.cpp b/tests/common/database_fixture.cpp
index 1bd48bc6..64400522 100644
--- a/tests/common/database_fixture.cpp
+++ b/tests/common/database_fixture.cpp
@@ -81,7 +81,7 @@ database_fixture::database_fixture()
    genesis_state.initial_timestamp = time_point_sec( GRAPHENE_TESTING_GENESIS_TIMESTAMP );
 
    genesis_state.initial_active_witnesses = 10;
-   for( int i = 0; i < genesis_state.initial_active_witnesses; ++i )
+   for( unsigned i = 0; i < genesis_state.initial_active_witnesses; ++i )
    {
       auto name = "init"+fc::to_string(i);
       genesis_state.initial_accounts.emplace_back(name,