diff --git a/libraries/chain/market_evaluator.cpp b/libraries/chain/market_evaluator.cpp
index 5fedbd02f8..56c9db82e8 100644
--- a/libraries/chain/market_evaluator.cpp
+++ b/libraries/chain/market_evaluator.cpp
@@ -248,6 +248,11 @@ void_result call_order_update_evaluator::do_apply(const call_order_update_operat
       call_obj = &*itr;
       old_collateralization = call_obj->collateralization();
       old_debt = call_obj->debt;
+      auto new_collateral = call_obj->collateral + o.delta_collateral.amount;
+      auto new_debt = *old_debt + o.delta_debt.amount;
+
+      // Forbid zero collateral with nonzero debt (avoids divide by zero when calculating call price below)
+      FC_ASSERT(!(new_collateral == 0 && new_debt != 0), "Cannot have zero collateral and nonzero debt");
 
       d.modify( *call_obj, [&]( call_order_object& call ){
          call.collateral += o.delta_collateral.amount;
diff --git a/libraries/db/include/graphene/db/generic_index.hpp b/libraries/db/include/graphene/db/generic_index.hpp
index 8a433264e1..8302881950 100644
--- a/libraries/db/include/graphene/db/generic_index.hpp
+++ b/libraries/db/include/graphene/db/generic_index.hpp
@@ -67,10 +67,25 @@ namespace graphene { namespace chain {
 
          virtual void modify( const object& obj, const std::function<void(object&)>& m )override
          {
-            assert( nullptr != dynamic_cast<const ObjectType*>(&obj) );
-            auto ok = _indices.modify( _indices.iterator_to( static_cast<const ObjectType&>(obj) ),
-                                       [&m]( ObjectType& o ){ m(o); } );
-            FC_ASSERT( ok, "Could not modify object, most likely a index constraint was violated" );
+            assert(nullptr != dynamic_cast<const ObjectType*>(&obj));
+            std::exception_ptr exc;
+            auto ok = _indices.modify(_indices.iterator_to(static_cast<const ObjectType&>(obj)),
+                                       [&m, &exc](ObjectType& o) mutable {
+                                          try {
+                                             m(o);
+                                          } catch (fc::exception e) {
+                                             exc = std::current_exception();
+                                             elog("Exception while modifying object: ${e} -- object may be corrupted",
+                                                  ("e", e));
+                                          } catch (...) {
+                                             exc = std::current_exception();
+                                             elog("Unknown exception while modifying object");
+                                          }
+                                       }
+                      );
+            if (exc)
+                std::rethrow_exception(exc);
+            FC_ASSERT(ok, "Could not modify object, most likely a index constraint was violated");
          }
 
          virtual void remove( const object& obj )override
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 5fd06115fd..ccdfc93d70 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -13,6 +13,10 @@ if(MSVC)
   set_source_files_properties( tests/serialization_tests.cpp PROPERTIES COMPILE_FLAGS "/bigobj" )
 endif(MSVC)
 
+file(GLOB SLOW_UNIT_TESTS "slow_tests/*.cpp")
+add_executable( slow_chain_test ${SLOW_UNIT_TESTS} ${COMMON_SOURCES} )
+target_link_libraries( slow_chain_test graphene_chain graphene_app graphene_account_history graphene_elasticsearch graphene_egenesis_none fc graphene_wallet ${PLATFORM_SPECIFIC_LIBS} )
+
 file(GLOB PERFORMANCE_TESTS "performance/*.cpp")
 add_executable( performance_test ${PERFORMANCE_TESTS} ${COMMON_SOURCES} )
 target_link_libraries( performance_test graphene_chain graphene_app graphene_account_history graphene_elasticsearch graphene_egenesis_none fc ${PLATFORM_SPECIFIC_LIBS} )
diff --git a/tests/tests/call_order_tests.cpp b/tests/slow_tests/call_order_tests.cpp
similarity index 100%
rename from tests/tests/call_order_tests.cpp
rename to tests/slow_tests/call_order_tests.cpp
diff --git a/tests/slow_tests/main.cpp b/tests/slow_tests/main.cpp
new file mode 100644
index 0000000000..405e7c1059
--- /dev/null
+++ b/tests/slow_tests/main.cpp
@@ -0,0 +1,40 @@
+/*
+ * Copyright (c) 2015 Cryptonomex, Inc., and contributors.
+ *
+ * The MIT License
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+#include <cstdlib>
+#include <iostream>
+#include <boost/test/included/unit_test.hpp>
+
+extern uint32_t GRAPHENE_TESTING_GENESIS_TIMESTAMP;
+
+boost::unit_test::test_suite* init_unit_test_suite(int argc, char* argv[]) {
+   std::srand(time(NULL));
+   std::cout << "Random number generator seeded to " << time(NULL) << std::endl;
+   const char* genesis_timestamp_str = getenv("GRAPHENE_TESTING_GENESIS_TIMESTAMP");
+   if( genesis_timestamp_str != nullptr )
+   {
+      GRAPHENE_TESTING_GENESIS_TIMESTAMP = std::stoul( genesis_timestamp_str );
+   }
+   std::cout << "GRAPHENE_TESTING_GENESIS_TIMESTAMP is " << GRAPHENE_TESTING_GENESIS_TIMESTAMP << std::endl;
+   return nullptr;
+}
diff --git a/tests/tests/database_tests.cpp b/tests/tests/database_tests.cpp
index 8546210df4..6b5ea8b96b 100644
--- a/tests/tests/database_tests.cpp
+++ b/tests/tests/database_tests.cpp
@@ -62,6 +62,32 @@ BOOST_AUTO_TEST_CASE( undo_test )
    }
 }
 
+/**
+ * Check that database modify() functors that throw do not get caught by boost, which will remove the object
+ */
+BOOST_AUTO_TEST_CASE(failed_modify_test)
+{ try {
+   database db;
+   // Create dummy object
+   const auto& obj = db.create<account_balance_object>([](account_balance_object& obj) {
+                     obj.owner = account_id_type(123);
+                  });
+   account_balance_id_type obj_id = obj.id;
+   BOOST_CHECK_EQUAL(obj.owner.instance.value, 123);
+
+   // Modify dummy object, check that changes stick
+   db.modify(obj, [](account_balance_object& obj) {
+      obj.owner = account_id_type(234);
+   });
+   BOOST_CHECK_EQUAL(obj_id(db).owner.instance.value, 234);
+
+   // Throw exception when modifying object, check that object still exists after
+   BOOST_CHECK_THROW(db.modify(obj, [](account_balance_object& obj) {
+      throw 5;
+   }), int);
+   BOOST_CHECK_NE((long)db.find_object(obj_id), (long)nullptr);
+} FC_LOG_AND_RETHROW() }
+
 BOOST_AUTO_TEST_CASE( flat_index_test )
 { try {
    ACTORS((sam));
diff --git a/tests/tests/operation_tests.cpp b/tests/tests/operation_tests.cpp
index 345500f7b3..e354bdf57c 100644
--- a/tests/tests/operation_tests.cpp
+++ b/tests/tests/operation_tests.cpp
@@ -145,6 +145,7 @@ BOOST_AUTO_TEST_CASE( call_order_update_test )
       GRAPHENE_REQUIRE_THROW( borrow( dan, bitusd.amount(80000), asset(0)), fc::exception );
       BOOST_TEST_MESSAGE( "attempting to claim all collateral without paying off debt" );
       GRAPHENE_REQUIRE_THROW( cover( dan, bitusd.amount(0), asset(20000)), fc::exception );
+      GRAPHENE_REQUIRE_THROW( cover( dan, bitusd.amount(0), asset(20000-1)), fc::exception );
 
       borrow( sam, bitusd.amount(1000), asset(10000));
       transfer( sam, dan, bitusd.amount(1000) );