diff --git a/src/fun.c b/src/fun.c
index 9c9a8b2..d329f5e 100644
--- a/src/fun.c
+++ b/src/fun.c
@@ -27,9 +27,7 @@
  * - Exits with an error if file loading or parsing fails.
  *
  * Example:
- * ```bash
  * $ fun script.fun
- * ```
  *
  * @author Johannes Findeisen
  * @date 2025-10-16
@@ -474,7 +472,7 @@ int main(int argc, char **argv) {
                 int filtered = (pattern && *pattern);
                 printf("=== globals%s%s ===\n", filtered ? " matching '" : "", filtered ? pattern : "");
                 if (filtered) printf("'\n");
-                for (int i = 0; i < VM_MAX_GLOBALS; ++i) {
+                for (int i = 0; i < MAX_GLOBALS; ++i) {
                     if (vm.globals[i].type == VAL_NIL) continue;
                     char *sv = value_to_string_alloc(&vm.globals[i]);
                     if (!filtered || (sv && strstr(sv, pattern))) {
diff --git a/src/parser.c b/src/parser.c
index 82dac43..d1cd362 100644
--- a/src/parser.c
+++ b/src/parser.c
@@ -88,7 +88,7 @@ static void calc_line_col(const char *src, size_t len, size_t pos, int *out_line
 
 /* very small global symbol table for LOAD_GLOBAL/STORE_GLOBAL */
 static struct {
-    char *names[VM_MAX_GLOBALS];
+    char *names[MAX_GLOBALS];
     int count;
 } G = { {0}, 0 };
 
@@ -96,8 +96,8 @@ static int sym_index(const char *name) {
     for (int i = 0; i < G.count; ++i) {
         if (strcmp(G.names[i], name) == 0) return i;
     }
-    if (G.count >= VM_MAX_GLOBALS) {
-        parser_fail(0, "Too many globals (max %d)", VM_MAX_GLOBALS);
+    if (G.count >= MAX_GLOBALS) {
+        parser_fail(0, "Too many globals (max %d)", MAX_GLOBALS);
         return 0;
     }
     G.names[G.count] = strdup(name);
@@ -106,7 +106,7 @@ static int sym_index(const char *name) {
 
 /* ---- locals environment for functions ---- */
 typedef struct {
-    char *names[FRAME_MAX_LOCALS];
+    char *names[MAX_FRAME_LOCALS];
     int count;
 } LocalEnv;
 
@@ -133,8 +133,8 @@ static int local_find(const char *name) {
 
 static int local_add(const char *name) {
     if (!g_locals) return -1;
-    if (g_locals->count >= FRAME_MAX_LOCALS) {
-        parser_fail(0, "Too many local variables/parameters (max %d)", FRAME_MAX_LOCALS);
+    if (g_locals->count >= MAX_FRAME_LOCALS) {
+        parser_fail(0, "Too many local variables/parameters (max %d)", MAX_FRAME_LOCALS);
         return -1;
     }
     int idx = g_locals->count++;
diff --git a/src/vm.c b/src/vm.c
index 7e48b31..1d9b8f2 100644
--- a/src/vm.c
+++ b/src/vm.c
@@ -85,10 +85,10 @@ Dev tips:
 
 static const char* value_type_name(ValueType t) {
     switch (t) {
-        case VAL_INT: return "int";
-        case VAL_STRING: return "string";
         case VAL_FUNCTION: return "function";
+        case VAL_INT: return "int";
         case VAL_NIL: return "nil";
+        case VAL_STRING: return "string";
         default: return "unknown";
     }
 }
@@ -115,7 +115,7 @@ void vm_reset(VM *vm) {
     // Clear stack
     vm->sp = -1;
     // Free globals
-    for (int i = 0; i < VM_MAX_GLOBALS; ++i) {
+    for (int i = 0; i < MAX_GLOBALS; ++i) {
         free_value(vm->globals[i]);
         vm->globals[i] = make_nil();
     }
@@ -125,7 +125,7 @@ void vm_reset(VM *vm) {
 
 void vm_dump_globals(VM *vm) {
     printf("=== globals ===\n");
-    for (int i = 0; i < VM_MAX_GLOBALS; ++i) {
+    for (int i = 0; i < MAX_GLOBALS; ++i) {
         if (vm->globals[i].type != VAL_NIL) {
             printf("[%d] ", i);
             print_value(&vm->globals[i]);
@@ -136,7 +136,7 @@ void vm_dump_globals(VM *vm) {
 }
 
 static void push_value(VM *vm, Value v) {
-    if (vm->sp >= VM_STACK_SIZE - 1) {
+    if (vm->sp >= STACK_SIZE - 1) {
         fprintf(stderr, "Runtime error: stack overflow\n");
         exit(1);
     }
@@ -154,7 +154,7 @@ static Value pop_value(VM *vm) {
 static void frame_init(Frame *f) {
     f->fn = NULL;
     f->ip = 0;
-    for (int i = 0; i < FRAME_MAX_LOCALS; ++i) f->locals[i] = make_nil();
+    for (int i = 0; i < MAX_FRAME_LOCALS; ++i) f->locals[i] = make_nil();
 }
 
 void vm_init(VM *vm) {
@@ -162,13 +162,13 @@ void vm_init(VM *vm) {
     vm->fp = -1;
     vm->output_count = 0;
     vm->instr_count = 0;
-    for (int i = 0; i < VM_MAX_GLOBALS; ++i)
+    for (int i = 0; i < MAX_GLOBALS; ++i)
         vm->globals[i] = make_nil();
 }
 
 /* push a new frame, transferring ownership of args[] into frame->locals[0..argc-1] */
 static void vm_push_frame(VM *vm, Bytecode *fn, int argc, Value *args) {
-    if (vm->fp >= VM_MAX_FRAMES - 1) {
+    if (vm->fp >= MAX_FRAMES - 1) {
         fprintf(stderr, "Runtime error: too many frames\n");
         exit(1);
     }
@@ -177,7 +177,7 @@ static void vm_push_frame(VM *vm, Bytecode *fn, int argc, Value *args) {
     f->fn = fn;
     f->ip = 0;
     /* move args into locals 0..argc-1 */
-    for (int i = 0; i < argc && i < FRAME_MAX_LOCALS; ++i) {
+    for (int i = 0; i < argc && i < MAX_FRAME_LOCALS; ++i) {
         f->locals[i] = args[i]; /* transfer ownership */
     }
 }
@@ -189,7 +189,7 @@ static void vm_pop_frame(VM *vm) {
         exit(1);
     }
     Frame *f = &vm->frames[vm->fp];
-    for (int i = 0; i < FRAME_MAX_LOCALS; ++i) {
+    for (int i = 0; i < MAX_FRAME_LOCALS; ++i) {
         free_value(f->locals[i]);
         f->locals[i] = make_nil();
     }
diff --git a/src/vm.h b/src/vm.h
index 6968711..cb2e0ff 100644
--- a/src/vm.h
+++ b/src/vm.h
@@ -7,25 +7,16 @@
  * https://opensource.org/license/isc-license-txt
  */
 
-/**
- * This file is part of the Fun programming language.
- * https://hanez.org/project/fun/
- *
- * Copyright 2025 Johannes Findeisen <you@hanez.org>
- * Licensed under the terms of the ISC license.
- * https://opensource.org/license/isc-license-txt
- */
-
 #ifndef FUN_VM_H
 #define FUN_VM_H
 
 #include "bytecode.h"
 
-#define VM_STACK_SIZE 1024
-#define VM_MAX_FRAMES 128
-#define VM_MAX_GLOBALS 128
-#define VM_OUTPUT_SIZE 1024
-#define FRAME_MAX_LOCALS 64
+#define MAX_FRAMES 128
+#define MAX_FRAME_LOCALS 64
+#define MAX_GLOBALS 128
+#define OUTPUT_SIZE 1024
+#define STACK_SIZE 1024
 
 static const char *opcode_names[] = {
     "NOP","LOAD_CONST","LOAD_LOCAL","STORE_LOCAL",
@@ -48,19 +39,19 @@ static const char *opcode_names[] = {
 typedef struct {
     Bytecode *fn;
     int ip;
-    Value locals[FRAME_MAX_LOCALS];
+    Value locals[MAX_FRAME_LOCALS];
 } Frame;
 
 typedef struct {
-    Value stack[VM_STACK_SIZE];
+    Value stack[STACK_SIZE];
     int sp;
 
-    Frame frames[VM_MAX_FRAMES];
+    Frame frames[MAX_FRAMES];
     int fp; // frame pointer, -1 when no frame
 
-    Value globals[VM_MAX_GLOBALS];
+    Value globals[MAX_GLOBALS];
 
-    Value output[VM_OUTPUT_SIZE]; // store printed values
+    Value output[OUTPUT_SIZE]; // store printed values
     int output_count;
 
     long long instr_count; // executed instructions in the last vm_run
diff --git a/src/vm/core/load_global.c b/src/vm/core/load_global.c
index ff83bf3..85a55f2 100644
--- a/src/vm/core/load_global.c
+++ b/src/vm/core/load_global.c
@@ -32,7 +32,7 @@
 
 case OP_LOAD_GLOBAL: {
     int idx = inst.operand;
-    if (idx < 0 || idx >= VM_MAX_GLOBALS) {
+    if (idx < 0 || idx >= MAX_GLOBALS) {
         fprintf(stderr, "Runtime error: global index out of range\n");
         exit(1);
     }
diff --git a/src/vm/core/load_local.c b/src/vm/core/load_local.c
index a3aceba..460357a 100644
--- a/src/vm/core/load_local.c
+++ b/src/vm/core/load_local.c
@@ -32,7 +32,7 @@
 
 case OP_LOAD_LOCAL: {
     int slot = inst.operand;
-    if (slot < 0 || slot >= FRAME_MAX_LOCALS) {
+    if (slot < 0 || slot >= MAX_FRAME_LOCALS) {
         fprintf(stderr, "Runtime error: local slot out of range\n");
         exit(1);
     }
diff --git a/src/vm/core/store_global.c b/src/vm/core/store_global.c
index 41c6b27..b40476b 100644
--- a/src/vm/core/store_global.c
+++ b/src/vm/core/store_global.c
@@ -32,7 +32,7 @@
 
 case OP_STORE_GLOBAL: {
     int idx = inst.operand;
-    if (idx < 0 || idx >= VM_MAX_GLOBALS) {
+    if (idx < 0 || idx >= MAX_GLOBALS) {
         fprintf(stderr, "Runtime error: global index out of range\n");
         exit(1);
     }
diff --git a/src/vm/core/store_local.c b/src/vm/core/store_local.c
index 69b7e54..e4b51da 100644
--- a/src/vm/core/store_local.c
+++ b/src/vm/core/store_local.c
@@ -32,7 +32,7 @@
 
 case OP_STORE_LOCAL: {
     int slot = inst.operand;
-    if (slot < 0 || slot >= FRAME_MAX_LOCALS) {
+    if (slot < 0 || slot >= MAX_FRAME_LOCALS) {
         fprintf(stderr, "Runtime error: local slot out of range\n");
         exit(1);
     }
diff --git a/src/vm/print.c b/src/vm/print.c
index d5efb16..78194eb 100644
--- a/src/vm/print.c
+++ b/src/vm/print.c
@@ -31,7 +31,7 @@ case OP_PRINT: {
     Value v = pop_value(vm);
     Value snap = deep_copy_value(&v);
     free_value(v);
-    if (vm->output_count < VM_OUTPUT_SIZE) {
+    if (vm->output_count < OUTPUT_SIZE) {
         vm->output[vm->output_count++] = snap;
     } else {
         free_value(snap);