diff --git a/inject/inject.vala b/inject/inject.vala
index fbb86b3e6..032d14b16 100644
--- a/inject/inject.vala
+++ b/inject/inject.vala
@@ -415,7 +415,7 @@ namespace Frida.Inject {
 			buf[n] = 0;
 
 			if (script_runner.terminal_mode == TerminalMode.BINARY) {
-				var bytes = new Bytes (buf[0:n]);
+				var bytes = new Bytes (buf[:n]);
 				script_runner.on_stdin ("", bytes);
 			} else {
 				script_runner.on_stdin ((string) buf, null);
@@ -740,14 +740,13 @@ namespace Frida.Inject {
 				return false;
 
 			var tuple = payload.get_array ();
-			if (tuple.get_length () < 1)
+			var tuple_len = tuple.get_length ();
+			if (tuple_len == 0)
 				return false;
 
-			var first_element = tuple.get_element (0);
-			if (first_element.get_value_type () != typeof (string))
+			var type = tuple.get_element (0).get_string ();
+			if (type == null)
 				return false;
-
-			var type = first_element.get_string ();
 			switch (type) {
 				case "frida:stdout":
 				case "frida:stderr":
@@ -756,26 +755,21 @@ namespace Frida.Inject {
 					return false;
 			}
 
-			if (tuple.get_length () > 1) {
-				var second_element = tuple.get_element (1);
-
-				if (second_element.get_value_type () != typeof (string))
+			if (tuple_len >= 2) {
+				var str = tuple.get_element (1).get_string ();
+				if (str == null)
 					return false;
 
-				var str = second_element.get_string ();
-
-				if (str != null) {
-					switch (type) {
-						case "frida:stdout":
-							stdout.write (str.data);
-							stdout.flush ();
-							break;
-						case "frida:stderr":
-							stderr.write (str.data);
-							break;
-						default:
-							return false;
-					}
+				switch (type) {
+					case "frida:stdout":
+						stdout.write (str.data);
+						stdout.flush ();
+						break;
+					case "frida:stderr":
+						stderr.write (str.data);
+						break;
+					default:
+						return false;
 				}
 			}
 
@@ -792,6 +786,7 @@ namespace Frida.Inject {
 						return false;
 				}
 			}
+
 			return true;
 		}
 
diff --git a/src/barebone/script.vala b/src/barebone/script.vala
index d99325709..fb769cc90 100644
--- a/src/barebone/script.vala
+++ b/src/barebone/script.vala
@@ -420,7 +420,7 @@ namespace Frida {
 
 		public void post (string json, Bytes? data) {
 			var json_val = ctx.make_string (json);
-			var data_val = ctx.make_array_buffer (data.get_data ());
+			var data_val = (data != null) ? ctx.make_array_buffer (data.get_data ()) : QuickJS.Null;
 			invoke_void (dispatch_message_func, { json_val, data_val }, runtime_obj);
 			ctx.free_value (data_val);
 			ctx.free_value (json_val);
diff --git a/src/host-session-service.vala b/src/host-session-service.vala
index cd8f01e08..1ac80ca60 100644
--- a/src/host-session-service.vala
+++ b/src/host-session-service.vala
@@ -1335,7 +1335,8 @@ namespace Frida {
 		protected virtual void on_event (string type, Json.Array event) {
 		}
 
-		protected async Json.Node call (string method, Json.Node[] args, Bytes? data, Cancellable? cancellable) throws Error, IOError {
+		protected async Json.Node call (string method, Json.Node[] args, Bytes? data, Cancellable? cancellable)
+				throws Error, IOError {
 			yield ensure_loaded (cancellable);
 
 			return yield rpc_client.call (method, args, data, cancellable);