diff --git a/antlr/pdp7asm.g4 b/antlr/pdp7asm.g4
index a6a799f..4c89111 100644
--- a/antlr/pdp7asm.g4
+++ b/antlr/pdp7asm.g4
@@ -123,6 +123,10 @@ opcode
     | 'sma'
     | 'skp'
     | 'law'
+    | 'xor'
+    | 'alss'
+    | 'sac'
+    | 'add'
     ;
 
 LOC