diff --git a/README.md b/README.md
index 2992174..8aa618a 100644
--- a/README.md
+++ b/README.md
@@ -60,6 +60,9 @@ classDiagram
 
 ```mermaid
 classDiagram
+    class Operand {
+        + Word getValue()
+    }
     class Instruction {
         + void execute(Memory memory, ProgramCounter pc)
         # String opcode()
@@ -73,15 +76,16 @@ classDiagram
     class JumpEq
     class Mul
     class Print
-    Instruction <|-- Word
-    Instruction <|-- Address
-    Add <|-- Instruction
-    Copy <|-- Instruction
-    Halt <|-- Instruction
-    Jump <|-- Instruction
-    JumpEq <|-- Instruction
-    Mul <|-- Instruction
-    Print <|-- Instruction
+    Instruction *-- Operand
+    Operand <|-- Word
+    Operand <|-- Address
+    Add --|> Instruction
+    Copy --|> Instruction
+    Halt --|> Instruction
+    Jump --|> Instruction
+    JumpEq --|> Instruction
+    Mul --|> Instruction
+    Print --|> Instruction
 ```
 
 ```mermaid