diff --git a/server/utils.js b/server/utils.js
index 26690b30..d4139d87 100644
--- a/server/utils.js
+++ b/server/utils.js
@@ -14,17 +14,57 @@ function isInBbox(position, bbox) {
 }
 
 function filterStreamPromise(inStream, filterFunction) {
-	return combine(
-		inStream,
-		es.map(function(data, callback) {
-			filterFunction(data).then(function(newData) {
-				if(newData == null)
-					callback();
-				else
-					callback(null, newData);
-			}).catch(callback);
-		})
-	);
+	var error = false;
+
+	var ret = new stream.Readable({ objectMode: true });
+
+	var running = false;
+	var queue = [ ];
+
+	function handleQueue() {
+		if(error || running)
+			return;
+
+		if(queue.length > 0) {
+			var next = queue.shift();
+			if(next == null) {
+				ret.push(null);
+			} else {
+				running = true;
+				Promise.resolve(filterFunction(next)).nodeify(function(err, newData) {
+					running = false;
+
+					if(error)
+						return;
+
+					if(err) {
+						error = true;
+						ret.emit("error", err);
+					} else if(newData != null) {
+						ret.push(newData);
+					}
+
+					setImmediate(handleQueue);
+				});
+			}
+		}
+	}
+
+	inStream.on("data", function(data) {
+		if(data != null)
+			queue.push(data);
+		handleQueue();
+	}).on("end", function() {
+		queue.push(null);
+		handleQueue();
+	}).on("error", function(err) {
+		ret.emit("error", err);
+	});
+
+	ret._read = function() {
+	};
+
+	return ret;
 }
 
 function extend(obj1, obj2) {