diff --git a/microscpi-macros/src/lib.rs b/microscpi-macros/src/lib.rs
index 9f21bbe..a401f94 100644
--- a/microscpi-macros/src/lib.rs
+++ b/microscpi-macros/src/lib.rs
@@ -107,7 +107,14 @@ impl CommandDefinition {
 
         quote! {
             #command_id => {
-                if args.len() != #arg_count {
+                let args_len = args.len();
+                if args_len == 0 && #arg_count > 0 {
+                    Err(::microscpi::Error::MissingParameter)
+                }
+                else if args_len > 0 && #arg_count == 0 {
+                    Err(::microscpi::Error::ParameterNotAllowed)
+                }
+                else if args_len != #arg_count {
                     Err(::microscpi::Error::UnexpectedNumberOfParameters)
                 }
                 else {