diff --git a/src/lang.zig b/src/lang.zig
index 89ed749..4db0cb7 100644
--- a/src/lang.zig
+++ b/src/lang.zig
@@ -453,7 +453,7 @@ pub const Lang = struct {
         self.line = 0;
     }
     fn doError(self: *Lang, comptime fmt: []const u8, args: var) void {
-        std.debug.warn("error at line {}: ", .{self.line});
+        std.debug.warn("ERROR! at line {}: ", .{self.line});
         std.debug.warn(fmt, args);
         std.debug.warn("\n", .{});
         self.has_error = true;
@@ -491,19 +491,21 @@ pub const Lang = struct {
             cmd.split = try std.fmt.parseInt(usize, split.?, 10);
             cmd.index = try std.fmt.parseInt(usize, index.?, 10);
 
+            // All parameters for LV2 plugins are f32.
             inline for (@typeInfo(@TypeOf(cmd.parameters)).Struct.fields) |cmd_field| {
-                const arg = tok_it.next().?;
+                const maybe_arg = tok_it.next();
+                if (maybe_arg == null) {
+                    self.doError("Expected parameter for {}, got nothing", .{cmd_field.name});
+                    return;
+                }
+
+                const arg = maybe_arg.?;
+
                 const argument_value = switch (cmd_field.field_type) {
                     f32 => try std.fmt.parseFloat(f32, arg),
                     else => @compileError("LV2 parameter struct can only have f32 fields"),
                 };
 
-                std.debug.warn("parsing {}, arg of type {} => {}\n", .{
-                    @typeName(command_struct),
-                    @typeName(@TypeOf(argument_value)),
-                    argument_value,
-                });
-
                 @field(cmd.parameters, cmd_field.name) = argument_value;
             }
         } else {