diff --git a/assembler.js b/assembler.js
index ca998d2..1c5e0a7 100644
--- a/assembler.js
+++ b/assembler.js
@@ -99,8 +99,19 @@ function preparseSourceCode(source) {
         info.argument = op_arg_array[1];
         info.extraArgument = op_arg_array[2];
       }
-      if (op_arg_array.length > 3) {
-        console.error('Error on line ${info.number}: Too many arguments');
+      // If there's too many arguments, throw an error
+      // NB. there's a special case:
+      // lines with the ASM_IP_LABEL can take an extra argument
+      let maxArgs = 2;
+      if (op_arg_array.length > 2 && op_arg_array[1].startsWith(ASM_IP_LABEL)) {
+        maxArgs = 3;
+      }
+      if (op_arg_array.length > maxArgs) {
+        console.error();
+        console.error(`Error: Too many arguments`);
+        console.error(` at line ${info.number}`);
+        console.error();
+        throw new Error("Too many arguments");
       }
     }
     return info;
@@ -226,7 +237,9 @@ function decodeInstructions(source) {
         //  then it's an error
         if (!line.operation.startsWith('@')) {
           if (mnemonicsWithOptionalArgs.indexOf(line.operation.toLowerCase()) < 0) {
-            console.error(`Missing operand for line ${line.number}: ${line.source}`);
+            console.error('');
+            console.error(`Error: Missing operand ${line.source}`);
+            console.error(`  at line ${line.number}`);
             console.error('');
             throw new Error("Missing operand");
           } else {