diff --git a/gen/generate_interpreter.js b/gen/generate_interpreter.js
index 02a9d902..0aa89fae 100755
--- a/gen/generate_interpreter.js
+++ b/gen/generate_interpreter.js
@@ -213,8 +213,9 @@ function gen_instruction_body_after_prefix(encodings, size)
                 }),
 
                 default_case: {
+                    varname: "x",
                     body: [
-                        `if DEBUG { panic!("Bad instruction at {:x}", *instruction_pointer); }`,
+                        `dbg_log!("#ud ${encoding.opcode.toString(16).toUpperCase()}/{} at {:x}", x, *instruction_pointer);`,
                         "trigger_ud();",
                     ],
                 }
@@ -413,7 +414,7 @@ function gen_table()
 
             "use crate::cpu::cpu::{after_block_boundary, modrm_resolve};",
             "use crate::cpu::cpu::{read_imm8, read_imm8s, read_imm16, read_imm32s, read_moffs};",
-            "use crate::cpu::cpu::{task_switch_test, trigger_ud, DEBUG};",
+            "use crate::cpu::cpu::{task_switch_test, trigger_ud};",
             "use crate::cpu::instructions;",
             "use crate::cpu::global_pointers::{instruction_pointer, prefixes};",
             "use crate::prefix;",
@@ -478,7 +479,6 @@ function gen_table()
             "use crate::cpu::cpu::{after_block_boundary, modrm_resolve};",
             "use crate::cpu::cpu::{read_imm8, read_imm16, read_imm32s};",
             "use crate::cpu::cpu::{task_switch_test, task_switch_test_mmx, trigger_ud};",
-            "use crate::cpu::cpu::DEBUG;",
             "use crate::cpu::instructions_0f;",
             "use crate::cpu::global_pointers::{instruction_pointer, prefixes};",
             "use crate::prefix;",
diff --git a/gen/rust_ast.js b/gen/rust_ast.js
index 23177801..60d7c285 100644
--- a/gen/rust_ast.js
+++ b/gen/rust_ast.js
@@ -32,7 +32,8 @@ export function print_syntax_tree(statements)
 
             if(statement.default_case)
             {
-                cases.push(`_ => {`);
+                const varname = statement.default_case.varname || "_";
+                cases.push(`${varname} => {`);
                 cases.push.apply(cases, indent(print_syntax_tree(statement.default_case.body), 4));
                 cases.push(`}`);
             }