diff --git a/src/query.cc b/src/query.cc
index 564d3c52..c8870fad 100644
--- a/src/query.cc
+++ b/src/query.cc
@@ -828,5 +828,34 @@ TEST_CASE("type usages") {
   REQUIRE(update.types_uses[0].to_add[0].range == Range(Position(2, 0)));
 }
 
+TEST_CASE("apply delta") {
+  IndexFile previous("foo.cc");
+  IndexFile current("foo.cc");
+
+  IndexFunc* pf = previous.Resolve(previous.ToFuncId("usr"));
+  IndexFunc* cf = current.Resolve(current.ToFuncId("usr"));
+  pf->callers.push_back(IndexFuncRef(IndexFuncId(0), Range(Position(1, 0))));
+  pf->callers.push_back(IndexFuncRef(IndexFuncId(0), Range(Position(2, 0))));
+  cf->callers.push_back(IndexFuncRef(IndexFuncId(0), Range(Position(4, 0))));
+  cf->callers.push_back(IndexFuncRef(IndexFuncId(0), Range(Position(5, 0))));
+
+  QueryDatabase db;
+  IdMap previous_map(&db, previous.id_cache);
+  IdMap current_map(&db, current.id_cache);
+  REQUIRE(db.funcs.size() == 1);
+
+  IndexUpdate import_update = IndexUpdate::CreateDelta(nullptr, &previous_map, nullptr, &previous);
+  IndexUpdate delta_update = IndexUpdate::CreateDelta(&previous_map, &current_map, &previous, &current);
+  
+  db.ApplyIndexUpdate(&import_update);
+  REQUIRE(db.funcs[0]->callers.size() == 2);
+  REQUIRE(db.funcs[0]->callers[0].loc.range == Range(Position(1, 0)));
+  REQUIRE(db.funcs[0]->callers[1].loc.range == Range(Position(2, 0)));
+
+  db.ApplyIndexUpdate(&delta_update);
+  REQUIRE(db.funcs[0]->callers.size() == 2);
+  REQUIRE(db.funcs[0]->callers[0].loc.range == Range(Position(4, 0)));
+  REQUIRE(db.funcs[0]->callers[1].loc.range == Range(Position(5, 0)));
+}
 
 TEST_SUITE_END();
\ No newline at end of file
diff --git a/src/utils.h b/src/utils.h
index d3389d2a..c276558b 100644
--- a/src/utils.h
+++ b/src/utils.h
@@ -75,12 +75,10 @@ void PushRange(std::queue<T>* dest, const std::vector<T>& to_add) {
 
 template<typename T>
 void RemoveRange(std::vector<T>* dest, const std::vector<T>& to_remove) {
-  auto it = std::remove_if(dest->begin(), dest->end(), [&](const T& t) {
+  dest->erase(std::remove_if(dest->begin(), dest->end(), [&](const T& t) {
     // TODO: make to_remove a set?
     return std::find(to_remove.begin(), to_remove.end(), t) != to_remove.end();
-  });
-  if (it != dest->end())
-    dest->erase(it);
+  }), dest->end());
 }
 
 // http://stackoverflow.com/a/38140932