diff --git a/mvt.cpp b/mvt.cpp
index 16481015..7589b4b3 100644
--- a/mvt.cpp
+++ b/mvt.cpp
@@ -115,11 +115,9 @@ bool mvt_tile::decode(const std::string &message, bool &was_compressed) {
 	std::string src;
 
 	if (is_compressed(message)) {
-		std::string uncompressed;
-		if (decompress(message, uncompressed) == 0) {
+		if (decompress(message, src) == 0) {
 			exit(EXIT_MVT);
 		}
-		src = uncompressed;
 		was_compressed = true;
 	} else {
 		src = message;
@@ -612,7 +610,10 @@ void mvt_layer::tag(mvt_feature &feature, std::string const &key, mvt_value cons
 	if (ki == key_map.end()) {
 		ko = keys.size();
 		keys.push_back(key);
-		key_map.emplace(key, ko);
+
+		if (key_map.size() < 200) {
+			key_map.emplace(key, ko);
+		}
 	} else {
 		ko = ki->second;
 	}
@@ -620,7 +621,10 @@ void mvt_layer::tag(mvt_feature &feature, std::string const &key, mvt_value cons
 	if (vi == value_map.end()) {
 		vo = values.size();
 		values.push_back(value);
-		value_map.emplace(value, vo);
+
+		if (value_map.size() < 200) {
+			value_map.emplace(value, vo);
+		}
 	} else {
 		vo = vi->second;
 	}