diff --git a/lib/mapObjects/JsonRandom.h b/lib/mapObjects/JsonRandom.h
index e39822113..ee0dd6299 100644
--- a/lib/mapObjects/JsonRandom.h
+++ b/lib/mapObjects/JsonRandom.h
@@ -32,7 +32,7 @@ namespace JsonRandom
 	};
 
 	DLL_LINKAGE si32 loadValue(const JsonNode & value, CRandomGenerator & rng, si32 defaultValue = 0);
-	DLL_LINKAGE std::string loadKey(const JsonNode & value, CRandomGenerator & rng, std::string defaultValue = "");
+	DLL_LINKAGE std::string loadKey(const JsonNode & value, CRandomGenerator & rng, const std::set<std::string> & valuesSet);
 	DLL_LINKAGE TResources loadResources(const JsonNode & value, CRandomGenerator & rng);
 	DLL_LINKAGE TResources loadResource(const JsonNode & value, CRandomGenerator & rng);
 	DLL_LINKAGE std::vector<si32> loadPrimary(const JsonNode & value, CRandomGenerator & rng);