diff --git a/test/test_map.cpp b/test/test_map.cpp
index c2e4527c..2c19e4e4 100644
--- a/test/test_map.cpp
+++ b/test/test_map.cpp
@@ -504,7 +504,7 @@ namespace
       CHECK(data.at(Key("0")) == compare_data.at("0"));
       CHECK(data.at(Key("1")) == compare_data.at("1"));
       CHECK(data.at(Key("2")) == compare_data.at("2"));
-      CHECK(data.at("3") == compare_data.at("3"));
+      CHECK(data.at(Key("3")) == compare_data.at("3"));
       CHECK(data.at(Key("4")) == compare_data.at("4"));
       CHECK(data.at(Key("5")) == compare_data.at("5"));
       CHECK(data.at(Key("6")) == compare_data.at("6"));