diff --git a/src/ast.h b/src/ast.h
index 12c9b79..8e4fc42 100644
--- a/src/ast.h
+++ b/src/ast.h
@@ -5,6 +5,7 @@
 #include "error.h"
 #include "lexer.h"
 #include "tokenlist.h"
+#include <assert.h>
 #include <stddef.h>
 #include <stdint.h>
 
@@ -75,10 +76,26 @@ typedef struct register_ {
 } register_t;
 
 typedef struct opcode_encoding {
-    uint8_t encoding[32];
+    uint8_t buffer[32];
     size_t len;
 } opcode_encoding_t;
 
+typedef struct instruction {
+    bool has_reference;
+    opcode_encoding_t encoding;
+    int64_t address;
+} instruction_t;
+
+typedef struct reference {
+    int64_t offset;
+    int64_t address;
+    operand_size_t size;
+} reference_t;
+
+typedef struct {
+    int64_t address;
+} label_t;
+
 struct ast_node {
     node_id_t id;
     tokenlist_entry_t *token_entry;
@@ -89,10 +106,37 @@ struct ast_node {
     union {
         register_t reg;
         number_t number;
-        opcode_encoding_t encoding;
+        instruction_t instruction;
+        reference_t reference;
+        label_t label;
     } value;
 };
 
+static inline register_t *ast_node_register_value(ast_node_t *node) {
+    assert(node->id == NODE_REGISTER);
+    return &node->value.reg;
+}
+
+static inline number_t *ast_node_number_value(ast_node_t *node) {
+    assert(node->id == NODE_NUMBER);
+    return &node->value.number;
+}
+
+static inline instruction_t *ast_node_instruction_value(ast_node_t *node) {
+    assert(node->id == NODE_INSTRUCTION);
+    return &node->value.instruction;
+}
+
+static inline reference_t *ast_node_reference_value(ast_node_t *node) {
+    assert(node->id == NODE_LABEL_REFERENCE);
+    return &node->value.reference;
+}
+
+static inline label_t *ast_node_label_value(ast_node_t *node) {
+    assert(node->id == NODE_LABEL);
+    return &node->value.label;
+}
+
 /**
  * @brief Allocates a new AST node
  *
diff --git a/src/encoder/encoder.c b/src/encoder/encoder.c
index 86c5263..d81a084 100644
--- a/src/encoder/encoder.c
+++ b/src/encoder/encoder.c
@@ -481,7 +481,7 @@ error_t *encoder_encode_instruction(encoder_t *encoder,
         return err;
 
     // produce the actual encoding output in the NODE_INSTRUCTION value
-    uint8_t *output = instruction->value.encoding.encoding;
+    uint8_t *output = instruction->value.instruction.encoding.buffer;
     size_t output_len = 0;
 
     // Handle prefixes
@@ -500,7 +500,7 @@ error_t *encoder_encode_instruction(encoder_t *encoder,
     memcpy(output + output_len, encoding->buffer, encoding->len);
     output_len += encoding->len;
 
-    instruction->value.encoding.len = output_len;
+    instruction->value.instruction.encoding.len = output_len;
 
     return nullptr;
 }
diff --git a/src/main.c b/src/main.c
index 17d9335..93e3aff 100644
--- a/src/main.c
+++ b/src/main.c
@@ -88,7 +88,8 @@ error_t *print_encoding(tokenlist_t *list) {
         if (node->id != NODE_INSTRUCTION)
             continue;
 
-        print_hex(node->value.encoding.len, node->value.encoding.encoding);
+        print_hex(node->value.instruction.encoding.len,
+                  node->value.instruction.encoding.buffer);
     }
 
     encoder_free(encoder);