diff --git a/packages/agoric-cli/src/anylogger-agoric.js b/packages/agoric-cli/src/anylogger-agoric.js
index 87bc1bb679f..c21c85a4dc0 100644
--- a/packages/agoric-cli/src/anylogger-agoric.js
+++ b/packages/agoric-cli/src/anylogger-agoric.js
@@ -3,14 +3,31 @@ import {
   getEnvironmentOption,
   getEnvironmentOptionsList,
 } from '@endo/env-options';
+import { defineName } from '@agoric/internal/src/js-utils.js';
+
 import anylogger from 'anylogger';
 import chalk from 'chalk';
 
+/**
+ * @import {BaseLevels} from 'anylogger';
+ * @typedef {keyof BaseLevels} LogLevel;
+ */
+
 const DEBUG_LIST = getEnvironmentOptionsList('DEBUG');
 
 // Turn on debugging output with DEBUG=agoric or DEBUG=agoric:${level}
-let selectedLevel =
-  DEBUG_LIST.length || getEnvironmentOption('DEBUG', 'unset') === 'unset'
+/**
+ * As documented in ../../../docs/env.md, the log level defaults to "log" when
+ * environment variable DEBUG is non-empty or `'unset'`,
+ * and to the quieter "info" when it is set to an empty string,
+ * but in either case is overridden if DEBUG
+ * is a comma-separated list that contains "agoric:none" or "agoric:${level}" or
+ * "agoric" (the last an alias for "agoric:debug").
+ *
+ * @type {string | undefined}
+ */
+let maxActiveLevel =
+  DEBUG_LIST.length > 0 || getEnvironmentOption('DEBUG', 'unset') === 'unset'
     ? 'log'
     : 'info';
 for (const level of DEBUG_LIST) {
@@ -19,29 +36,35 @@ for (const level of DEBUG_LIST) {
     continue;
   }
   if (parts.length > 1) {
-    selectedLevel = parts[1];
+    maxActiveLevel = parts[1];
   } else {
-    selectedLevel = 'debug';
+    maxActiveLevel = 'debug';
   }
 }
-const selectedCode = anylogger.levels[selectedLevel];
-const globalCode = selectedCode === undefined ? -Infinity : selectedCode;
+const selectedCode = anylogger.levels[maxActiveLevel];
+const maxActiveLevelCode =
+  selectedCode === undefined ? -Infinity : selectedCode;
 
 const oldExt = anylogger.ext;
-anylogger.ext = (l, ...rest) => {
-  l = oldExt(l, ...rest);
-  l.enabledFor = lvl => globalCode >= anylogger.levels[lvl];
+anylogger.ext = logger => {
+  logger = oldExt(logger);
+
+  /** @type {(level: LogLevel) => boolean} */
+  const enabledFor = level => anylogger.levels[level] <= maxActiveLevelCode;
+  logger.enabledFor = enabledFor;
 
-  const prefix = l.name.replace(/:/g, ': ');
+  const prefix = logger.name.replace(/:/g, ': ');
   for (const [level, code] of Object.entries(anylogger.levels)) {
-    if (globalCode >= code) {
+    if (maxActiveLevelCode >= code) {
       // Enable the printing with a prefix.
-      const doLog = l[level] || (() => {});
-      l[level] = (...args) => doLog(chalk.bold.blue(`${prefix}:`), ...args);
+      const doLog = logger[level] || defineName(`dummy ${level}`, () => {});
+      logger[level] = defineName(level, (...args) =>
+        doLog(chalk.bold.blue(`${prefix}:`), ...args),
+      );
     } else {
       // Disable printing.
-      l[level] = () => {};
+      logger[level] = defineName(`dummy ${level}`, () => {});
     }
   }
-  return l;
+  return logger;
 };
diff --git a/packages/cosmic-swingset/src/anylogger-agoric.js b/packages/cosmic-swingset/src/anylogger-agoric.js
index 9949e1e486a..5dbdc227183 100644
--- a/packages/cosmic-swingset/src/anylogger-agoric.js
+++ b/packages/cosmic-swingset/src/anylogger-agoric.js
@@ -3,23 +3,23 @@ import {
   getEnvironmentOptionsList,
   getEnvironmentOption,
 } from '@endo/env-options';
-import anylogger from 'anylogger';
 import { defineName } from '@agoric/internal/src/js-utils.js';
 
-/** @import {BaseLevels} from 'anylogger'; */
-/** @typedef {keyof BaseLevels} LogLevel; */
+import anylogger from 'anylogger';
 
-const VAT_LOGGER_PREFIXES = Object.freeze([
-  'SwingSet:vat',
-  'SwingSet:ls', // "ls" for "liveslots"
-]);
+/**
+ * @import {BaseLevels} from 'anylogger';
+ * @typedef {keyof BaseLevels} LogLevel;
+ */
 
 const DEBUG_LIST = getEnvironmentOptionsList('DEBUG');
 
+// Turn on debugging output with DEBUG=agoric or DEBUG=agoric:${level}
 /**
  * As documented in ../../../docs/env.md, the log level defaults to "log" when
- * environment variable DEBUG is non-empty or unset, and to the quieter "info"
- * when it is set to an empty string, but in either case is overridden if DEBUG
+ * environment variable DEBUG is non-empty or `'unset'`,
+ * and to the quieter "info" when it is set to an empty string,
+ * but in either case is overridden if DEBUG
  * is a comma-separated list that contains "agoric:none" or "agoric:${level}" or
  * "agoric" (the last an alias for "agoric:debug").
  *
@@ -40,6 +40,11 @@ const maxActiveLevelCode = /** @type {number} */ (
   (maxActiveLevel && anylogger.levels[maxActiveLevel]) ?? -Infinity
 );
 
+const VAT_LOGGER_PREFIXES = harden([
+  'SwingSet:vat',
+  'SwingSet:ls', // "ls" for "liveslots"
+]);
+
 const oldExt = anylogger.ext;
 anylogger.ext = logger => {
   logger = oldExt(logger);