diff --git a/asm.js b/asm.js
index c687de7..87ce8fa 100644
--- a/asm.js
+++ b/asm.js
@@ -61,6 +61,7 @@ const Action = Object.freeze({
     FUNC:   2,
     RESULT: 3,
     PARAM:  4,
+    SYMBOL: 5,
 });
 
 const types = {
@@ -99,8 +100,13 @@ class Parser {
         this.params = {};
 	}
 
+    integer(token) {
+        const x = parseInt(token);
+        return Number.isNaN(x) ? null : x;
+    }
+
     translate_code(token) {
-        return opcodes[token] ?? parseInt(token);
+        return opcodes[token] ?? this.integer(token);
     }
 
     translate_type(token) {
@@ -116,7 +122,10 @@ class Parser {
             return;
         }
         const code = this.translate_code(token);
-        return { type: Action.APPEND, code };
+        if (code)
+            return { type: Action.APPEND, code };
+        else
+            return { type: Action.SYMBOL, symbol: token };
     }
 
     token_export(token) {
@@ -155,7 +164,7 @@ class Parser {
     token_param_type(token) {
         if (token == LINE_END) {
             console.error(
-                "ERROR: Unexpected newline in .params: expected type");
+                "ERROR: Unexpected newline in .param: expected type");
             this.state = State.TOP;
             this.params = {};
         } else {
@@ -192,6 +201,7 @@ export class Assembler {
             [Action.FUNC]:   (action) => this.action_func(action),
             [Action.RESULT]: (action) => this.action_result(action),
             [Action.PARAM]:  (action) => this.action_param(action),
+            [Action.SYMBOL]: (action) => this.action_symbol(action),
         };
 
         this.exports = [];
@@ -225,6 +235,12 @@ export class Assembler {
         Object.assign(this.funcs[this.current_func].params, action.params);
     }
 
+    action_symbol(action) {
+        const func = this.funcs[this.current_func];
+        const index = Object.keys(func.params).indexOf(action.symbol);
+        func.body.push(index);
+    }
+
 	push(chunk) {
 		const text = this.decoder.decode(chunk, { stream: true });
 		for (const action of this.parser.handle(text))